Start async tasks on app start, await on later button click

I have a Windows 10 UWP application that I want to start intialising some classes asap, and only later need them to be complete.

I am new to multithreaded programming so apologies for apparent stupidity of my approach.

I started a task in the App constructor, assigning the task to a static property:

sealed partial class App : Application {
    ...
    internal static Task CoreIntialisationTask { get; set; }

    public App() {
        this.InitializeComponent();

        CoreIntialisationTask = StartInitialisation();

        this.Suspending += OnSuspending;
    }

    private async Task StartInitialisation() {
        await InitialiseService1Async();
        var service2Task = this.InitializeService2Async();
        var service3Task = this.InitializeService3Async();
        await service2Task;
        await service3Task;
    }

    ...
}

Then in my first loaded page, on a button click, is the latest possible moment when these services need to be fully initialised, so I added a check status and await call:

private async void btnStart_Click(object sender, RoutedEventArgs e) 
{
    if (App.CoreIntialisationTask.Status == TaskStatus.Running)
    {
        await App.CoreIntialisationTask;
        ...
    }
    ...
}

However, the CoreIntialisationTask Status at this point is Failure with the following inner Exception:

(new System.Threading.Tasks.SystemThreadingTasks_FutureDebugView<System.Threading.Tasks.VoidTaskResult>(App.CoreIntialisationTask).Exception).InnerException.Message
The application called an interface that was marshalled for a different thread. (Exception from HRESULT: 0x8001010E (RPC_E_WRONG_THREAD))

at Windows.UI.Xaml.Application.get_Resources()
at MyApplication.App.<InitializeService>d__26.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.GetResult()
at MyApplication.App.<StartInitialisation>d__25.MoveNext()

The StartInitialisation() method seems to get to the await service2Task but never the await service3Task; line.

Am I approaching this completely the wrong way or is there something more minor I am missing here?

You need to check server status or process.
If you need server you can use like:

Public Sub StratServices(ByVal servername As String)
    Try
        Dim service As ServiceController = New ServiceController(servername)
        If service.Status = ServiceControllerStatus.Stopped Then
            service.Start()
            service.Refresh()
        End If
    Catch ex As Exception
        MsgBox("You dont have Sql Srver in your Machine")
    End Try
End Sub

By use System.Serviceprocess