Trouble Converting Smart Card Program to UWP

I'm working on converting what was originally a web forms .NET application to UWP. The application is for using company-issued badges to record meeting attendance instead of our current paper sign in sheets. The original program uses an Omnikey 5427 CK in keyboard wedge mode and has no problems. For the new one running Windows 10 IoT Core on a Raspberry Pi 3B I'm trying more direct communication with the card reader so I don't have to rely on keyboard wedge and so I can gather more information from the card more quickly.

I've tried using the Microsoft Smart Card sample at https://github.com/Microsoft/Windows-universal-samples/tree/master/Samples/SmartCard/cs. The closest existing SO answer at Contact-less card through an OmniKey, how to get "UID"? got me to a GitHub repository https://github.com/StormRider01/ProxCardDemo2/blob/master/prox.cs. Both repos see the reader on my Windows 10 computer but not on the IoT device. As you can see from this screenshot (https://github.com/NevadaDonorNetwork/FSK-Prox-Card-Demo/blob/master/FSK%20Prox%20Card%20Demo/Screenshot_2019-04-04_13-49-14.jpg) the IoT device is detecting the card reader.

I've put together a repo at https://github.com/NevadaDonorNetwork/FSK-Prox-Card-Demo to text based on the SO solution I found.

// MainPage.xaml.cs
using System;
using System.Diagnostics;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;

// The Blank Page item template is documented at https://go.microsoft.com/fwlink/?LinkId=402352&clcid=0x409

namespace FSK_Prox_Card_Demo
{
    /// <summary>
    /// An empty page that can be used on its own or navigated to within a Frame.
    /// </summary>
    public sealed partial class MainPage : Page
    {
        public MainPage()
        {
            InitializeComponent();
            LoadCardReaders();
        }
        private void BtnRefreshReaders_Click(object sender, RoutedEventArgs e)
        {
            LoadCardReaders();
        }
        void X_CardPresented(string reader, byte[] cardData)
        {
            // Clear form labels
            TxtFacilityCode.Text = string.Empty;
            TxtBadgeNumber.Text = string.Empty;
            try
            {
                // load and parse ATR for facility code and and badge number
                string ATR = SCARD.ToHex(cardData, string.Empty);
                string CardFormat = ATR.Substring(0, 4);
                string ProxFormatSetting = ATR.Substring(4, 2);
                string StrFacilityCode = ATR.Substring(6, 4);
                string StrCardNumber = ATR.Substring(10, 6);
                // ensure facility code and and badge number are integers
                if (!int.TryParse(StrFacilityCode, out int FacilityCode))
                {
                    Debug.WriteLine("Invalid Facility Code:" + StrFacilityCode);
                    return;
                }
                if (!int.TryParse(StrCardNumber, out int CardNumber))
                {
                    Debug.WriteLine("Invalid Card Number: " + StrCardNumber);
                    return;
                }
                // write facility code and and badge number to output
                TxtFacilityCode.Text = FacilityCode.ToString();
                TxtBadgeNumber.Text = CardNumber.ToString();
                Debug.WriteLine("Facility Code (FAC): " + FacilityCode.ToString());
                Debug.WriteLine("Card Number (CN): " + CardNumber.ToString());
            }
            catch (Exception ex)
            {
                Debug.WriteLine(ex.Message);
                TxtOutput.Text += ex.Message + "\n";
            }
        }
        void LoadCardReaders()
        {
            // query readers
            ReaderList x = new ReaderList();
            x.CardPresented += X_CardPresented;
            x.Refresh();
            TxtOutput.Text += x.ReaderCount.ToString() + " readers found.\n";
        }
    }
}

// ProxCard2.cs
// based on Chris's response here: http://stackoverflow.com/questions/4497671/contact-less-card-through-an-omnikey-how-to-get-uid/14939168#14939168
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading;
namespace FSK_Prox_Card_Demo
{
    public delegate void VoidDelegate();
    public delegate void CardPresented(string reader, byte[] cardData);

    public class ReaderList : IDisposable, IEnumerable<string>
    {
        public ReaderList()
        { }

        public void Dispose()
        {
            StopThread();
        }

        private Thread thread;
        private void StartThread()
        {
            if (thread != null)
                StopThread();

            thread = new Thread(Run)
            {
                IsBackground = true
            };
            bStopThread = false;
            thread.Start();
        }

        private void StopThread()
        {
            if (thread != null)
            {
                bStopThread = true;
                Thread.Sleep(50);
            }
            if (thread != null)
                thread.Abort();
            if (thread != null)
                thread.Join();
            thread = null;
        }

        private List<string> readerNames = new List<string>();
        private Dictionary<string, string> lastCardFound = new Dictionary<string, string>();
        public int ReaderCount
        { get { return readerNames.Count; } }

        public void Refresh()
        {
            if (thread == null)
                StartThread();
        }

        public event VoidDelegate ListChanged;
        public event CardPresented CardPresented;

        private bool bStopThread = true;
        private void Run()
        {
            IntPtr hContext = IntPtr.Zero;

            try
            {
                uint result = SCARD.EstablishContext(SCARD.SCOPE_SYSTEM, IntPtr.Zero, IntPtr.Zero, ref hContext);
                if (result != SCARD.S_SUCCESS)
                {
                    thread = null;
                    return;
                }

                uint notification_state = SCARD.STATE_UNAWARE;

                while (!bStopThread)    // loop 1 - build list, then iterate
                {
                    SCARD.ReaderState[] states = new SCARD.ReaderState[ReaderCount + 1];
                    states[0] = new SCARD.ReaderState(@"\\?PNP?\NOTIFICATION")
                    {
                        dwCurrentState = notification_state
                    };

                    int iState = 0;
                    if (readerNames != null)
                        foreach (string s in readerNames)
                        {
                            iState++;
                            states[iState] = new SCARD.ReaderState(s)
                            {
                                dwCurrentState = SCARD.STATE_UNAWARE
                            };
                        }

                    while (!bStopThread)    // loop 2 - iterate over list built above
                    {
                        result = SCARD.GetStatusChange(hContext, 250, states, (uint)states.Length);
                        if (result == SCARD.E_TIMEOUT)
                            continue;
                        if (result != SCARD.S_SUCCESS)
                            break;

                        bool bReaderListChanged = false;
                        for (int i = 0; i < states.Length; i++)
                            if ((states[i].dwEventState & SCARD.STATE_CHANGED) != 0)
                                if (i == 0)
                                {
                                    // reader added or removed
                                    notification_state = states[0].dwEventState;

                                    // we want to replace the member in one step, rather than modifying it...
                                    List<string> tmp = GetReaderList(hContext, SCARD.GROUP_ALL_READERS);
                                    if (tmp == null)
                                        readerNames.Clear();
                                    else
                                        readerNames = tmp;

                                    ListChanged?.Invoke();
                                    bReaderListChanged = true;
                                }
                                else
                                {
                                    // card added or removed
                                    states[i].dwCurrentState = states[i].dwEventState;

                                    if ((states[i].dwEventState & SCARD.STATE_PRESENT) != 0)
                                    {
                                        byte[] cardData = new byte[states[i].cbATR];
                                        for (int j = 0; j < cardData.Length; j++)
                                            cardData[j] = states[i].rgbATR[j];
                                        string thisCard = SCARD.ToHex(cardData, "");
                                        lastCardFound.TryGetValue(states[i].szReader, out string lastCard);
                                        if (thisCard != lastCard)
                                        {
                                            lastCardFound[states[i].szReader] = thisCard;
                                            CardPresented?.Invoke(states[i].szReader, cardData);
                                        }
                                    }
                                    else
                                        lastCardFound[states[i].szReader] = "";
                                }

                        if (bReaderListChanged)
                            break;  // break out of loop 2, and re-build our 'states' list

                    } // end loop 2
                } // end loop 1
            }
            catch (Exception ex)
            {
                Debug.WriteLine(ex.Message);
            }
            finally
            {
                if (hContext != IntPtr.Zero)
                    SCARD.ReleaseContext(hContext);
                thread = null;
            }
        }

        private List<string> GetReaderList(IntPtr hContext, string sGroup)
        {
            uint nStringLength = 0;
            uint result = SCARD.ListReaders(hContext, sGroup, null, ref nStringLength);
            if (result != SCARD.S_SUCCESS)
                return null;

            string sReaders = new string(' ', (int)nStringLength);
            result = SCARD.ListReaders(hContext, sGroup, sReaders, ref nStringLength);
            if (result != SCARD.S_SUCCESS)
                return null;
            List<string> list = new List<string>(sReaders.Split('\0'));
            for (int i = 0; i < list.Count;)
                if (list[i].Trim().Length > 0)
                    i++;
                else
                    list.RemoveAt(i);
            return list;
        }

        public IEnumerator<string> GetEnumerator()
        { return readerNames.GetEnumerator(); }

        System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator()
        { return readerNames.GetEnumerator(); }

    }

    public class SCARD
    {
        [DllImport("WinScard.dll", EntryPoint = "SCardEstablishContext")]
        public static extern uint EstablishContext(
            uint dwScope,
            IntPtr nNotUsed1,
            IntPtr nNotUsed2,
            ref IntPtr phContext);

        [DllImport("WinScard.dll", EntryPoint = "SCardReleaseContext")]
        public static extern uint ReleaseContext(
            IntPtr hContext);

        [DllImport("winscard.dll", EntryPoint = "SCardGetStatusChangeW", CharSet = CharSet.Unicode)]
        public static extern uint GetStatusChange(
            IntPtr hContext,
            uint dwTimeout,
            [In, Out, MarshalAs(UnmanagedType.LPArray, SizeParamIndex = 3)]
                SCARD.ReaderState[] rgReaderState,
            uint cReaders);

        [DllImport("winscard.dll", EntryPoint = "SCardListReadersW", CharSet = CharSet.Unicode)]
        public static extern uint ListReaders(
            IntPtr hContext,
            string groups,
            string readers,
            ref uint size);

        #region Error codes
        public const uint S_SUCCESS = 0x00000000;
        public const uint F_INTERNAL_ERROR = 0x80100001;
        public const uint E_CANCELLED = 0x80100002;
        public const uint E_INVALID_HANDLE = 0x80100003;
        public const uint E_INVALID_PARAMETER = 0x80100004;
        public const uint E_INVALID_TARGET = 0x80100005;
        public const uint E_NO_MEMORY = 0x80100006;
        public const uint F_WAITED_TOO_LONG = 0x80100007;
        public const uint E_INSUFFICIENT_BUFFER = 0x80100008;
        public const uint E_UNKNOWN_READER = 0x80100009;
        public const uint E_TIMEOUT = 0x8010000A;
        public const uint E_SHARING_VIOLATION = 0x8010000B;
        public const uint E_NO_SMARTCARD = 0x8010000C;
        public const uint E_UNKNOWN_CARD = 0x8010000D;
        public const uint E_CANT_DISPOSE = 0x8010000E;
        public const uint E_PROTO_MISMATCH = 0x8010000F;
        public const uint E_NOT_READY = 0x80100010;
        public const uint E_INVALID_VALUE = 0x80100011;
        public const uint E_SYSTEM_CANCELLED = 0x80100012;
        public const uint F_COMM_ERROR = 0x80100013;
        public const uint F_UNKNOWN_ERROR = 0x80100014;
        public const uint E_INVALID_ATR = 0x80100015;
        public const uint E_NOT_TRANSACTED = 0x80100016;
        public const uint E_READER_UNAVAILABLE = 0x80100017;
        public const uint P_SHUTDOWN = 0x80100018;
        public const uint E_PCI_TOO_SMALL = 0x80100019;
        public const uint E_READER_UNSUPPORTED = 0x8010001A;
        public const uint E_DUPLICATE_READER = 0x8010001B;
        public const uint E_CARD_UNSUPPORTED = 0x8010001C;
        public const uint E_NO_SERVICE = 0x8010001D;
        public const uint E_SERVICE_STOPPED = 0x8010001E;
        public const uint E_UNEXPECTED = 0x8010001F;
        public const uint E_ICC_INSTALLATION = 0x80100020;
        public const uint E_ICC_CREATEORDER = 0x80100021;
        public const uint E_UNSUPPORTED_FEATURE = 0x80100022;
        public const uint E_DIR_NOT_FOUND = 0x80100023;
        public const uint E_FILE_NOT_FOUND = 0x80100024;
        public const uint E_NO_DIR = 0x80100025;
        public const uint E_NO_FILE = 0x80100026;
        public const uint E_NO_ACCESS = 0x80100027;
        public const uint E_WRITE_TOO_MANY = 0x80100028;
        public const uint E_BAD_SEEK = 0x80100029;
        public const uint E_INVALID_CHV = 0x8010002A;
        public const uint E_UNKNOWN_RES_MNG = 0x8010002B;
        public const uint E_NO_SUCH_CERTIFICATE = 0x8010002C;
        public const uint E_CERTIFICATE_UNAVAILABLE = 0x8010002D;
        public const uint E_NO_READERS_AVAILABLE = 0x8010002E;
        public const uint E_COMM_DATA_LOST = 0x8010002F;
        public const uint E_NO_KEY_CONTAINER = 0x80100030;
        public const uint W_UNSUPPORTED_CARD = 0x80100065;
        public const uint W_UNRESPONSIVE_CARD = 0x80100066;
        public const uint W_UNPOWERED_CARD = 0x80100067;
        public const uint W_RESET_CARD = 0x80100068;
        public const uint W_REMOVED_CARD = 0x80100069;
        public const uint W_SECURITY_VIOLATION = 0x8010006A;
        public const uint W_WRONG_CHV = 0x8010006B;
        public const uint W_CHV_BLOCKED = 0x8010006C;
        public const uint W_EOF = 0x8010006D;
        public const uint W_CANCELLED_BY_USER = 0x8010006E;
        public const uint W_CARD_NOT_AUTHENTICATED = 0x8010006F;
        #endregion

        public const uint SCOPE_USER = 0;
        public const uint SCOPE_TERMINAL = 1;
        public const uint SCOPE_SYSTEM = 2;

        public const string GROUP_ALL_READERS = "SCard$AllReaders\0\0";
        public const string GROUP_DEFAULT_READERS = "SCard$DefaultReaders\0\0";
        public const string GROUP_LOCAL_READERS = "SCard$LocalReaders\0\0";
        public const string GROUP_SYSTEM_READERS = "SCard$SystemReaders\0\0";

        public const uint STATE_UNAWARE = 0x00000000;
        public const uint STATE_IGNORE = 0x00000001;
        public const uint STATE_CHANGED = 0x00000002;
        public const uint STATE_UNKNOWN = 0x00000004;
        public const uint STATE_UNAVAILABLE = 0x00000008;
        public const uint STATE_EMPTY = 0x00000010;
        public const uint STATE_PRESENT = 0x00000020;
        public const uint STATE_ATRMATCH = 0x00000040;
        public const uint STATE_EXCLUSIVE = 0x00000080;
        public const uint STATE_INUSE = 0x00000100;
        public const uint STATE_MUTE = 0x00000200;
        public const uint STATE_UNPOWERED = 0x00000400;

        [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
        public struct ReaderState
        {
            public ReaderState(string sName)
            {
                szReader = sName;
                pvUserData = IntPtr.Zero;
                dwCurrentState = 0;
                dwEventState = 0;
                cbATR = 0;
                rgbATR = null;
            }

            internal string szReader;
            internal IntPtr pvUserData;
            internal uint dwCurrentState;
            internal uint dwEventState;
            internal uint cbATR;    // count of bytes in rgbATR
            [MarshalAs(UnmanagedType.ByValArray, SizeConst = 0x24, ArraySubType = UnmanagedType.U1)]
            internal byte[] rgbATR;
        }

        public static string ToHex(byte[] ab, string sDelim)
        {
            if (ab == null) return "<NULL>";
            return ToHex(ab, 0, ab.Length, sDelim);
        }

        public static string ToHex(byte[] ab, int offset, int len, string sDelim)
        {
            if (ab == null) return "<NULL>";
            StringBuilder sb = new StringBuilder();
            len = Math.Min(offset + len, ab.Length);
            for (int i = offset; i < len; i++)
                sb.Append(String.Format("{0:x02}", ab[i]).ToUpper() + sDelim);
            return sb.ToString();
        }
    }
}

I'm hoping to get the IoT device to read the facility code and badge number off of the proximity card when swiped.

I feel very close as the IoT Core Default Application does see the reader by the UWP example does not.

Yes, you're right. Default App is also UWP application.

Please check capabilities and ConnectedDevicePresenter.cs of default app as reference for modifying your application.