Adding WinUI Desktop Window inside WinUI UWP app

Using Windows UI Library 3 Preview 2 (July 2020) that was released just yesterday. On latest version of VS2019 - Preview, followed this official tutorial Get started with WinUI 3 for UWP apps to create a desktop project. Project successfully compiles but gives the following error when I click on the link Go to WinUI desktop window at the MainPage.xaml page. This link is supposed to open the WinUI Desktop Windows that I added as explained in step 7 of this MS team's tutorial. The error occurs at the constructor of the MainWindow.xaml.cs file. I'm using Windows10 Pro ver. 1903:

System.AccessViolationException HResult=0x80004003 Message=Attempted to read or write protected memory. This is often an indication that other memory is corrupt. Source= StackTrace:

MainPage.xaml:

<Page
    x:Class="WinUI_UWPTest.MainPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
....
    Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
    
    <Grid>
        <HyperlinkButton x:Name="hlbtnTest" Content="Go to WinUI desktop window" Click="hlbtnTest_Click"/>
        <Frame x:Name="frameMain"/>
    </Grid>
</Page>

MainPage.xaml.cs:

public sealed partial class MainPage : Page
{
    public MainPage()
    {
        this.InitializeComponent();
    }

    private void hlbtnTest_Click(object sender, RoutedEventArgs e)
    {
        frameMain.Navigate(typeof(BlankWindow1));
    }
}

BlankWindow1.xaml:

<Window
    x:Class="WinUI_UWPTest.BlankWindow1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
.....
    mc:Ignorable="d">

    <Grid>
        <TextBlock>WinUI Desktop Window</TextBlock>
    </Grid>
</Window>

BlankWindow1.xaml.cs: Error occurs at InitializeComponent(); line below:

public sealed partial class BlankWindow1 : Window
{
    public BlankWindow1()
    {
        this.InitializeComponent();
    }
}

App.xaml:

<Application
    x:Class="WinUI_UWPTest.App"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:WinUI_UWPTest">
    <Application.Resources>
        <ResourceDictionary>
            <ResourceDictionary.MergedDictionaries>
                <XamlControlsResources xmlns="using:Microsoft.UI.Xaml.Controls" />
                <!-- Other merged dictionaries here -->
            </ResourceDictionary.MergedDictionaries>
            <!-- Other app resources here -->
        </ResourceDictionary>
    </Application.Resources>
</Application>