Invalid Operation Exception while trying to show a ContentDialog at reactive_commandParameter

[DevTKSS]

Exception Details:
System.InvalidOperationException
  HResult=0x80131509
  Nachricht = The dependency property system should not be accessed from non UI thread.
  Quelle = Uno.UI
  Stapelüberwachung:
   bei Microsoft.UI.Xaml.DependencyProperty.GetProperty(Type type, String name)
   bei Microsoft.UI.Xaml.DependencyObjectStore.GetLocalPropertyDetails(DependencyProperty property)
   bei Microsoft.UI.Xaml.DependencyObjectStore.OnParentPropertyChangedCallback(ManagedWeakReference sourceInstance, DependencyProperty parentProperty, Object newValue)
   bei Microsoft.UI.Xaml.DependencyObjectStore.CallChildCallback(DependencyObjectStore childStore, ManagedWeakReference instanceRef, DependencyProperty property, Object newValue)
   bei Microsoft.UI.Xaml.DependencyObjectStore.InvokeCallbacks(DependencyObject actualInstanceAlias, DependencyProperty property, DependencyPropertyDetails propertyDetails, Object previousValue, DependencyPropertyValuePrecedences previousPrecedence, Object newValue, DependencyPropertyValuePrecedences newPrecedence, Boolean bypassesPropagation)
   bei Microsoft.UI.Xaml.DependencyObjectStore.InnerSetValue(DependencyProperty property, Object value, DependencyPropertyValuePrecedences precedence, DependencyPropertyDetails propertyDetails, Boolean isPersistentResourceBinding)
   bei Microsoft.UI.Xaml.DependencyObjectStore.SetValue(DependencyProperty property, Object value)
   bei Microsoft.UI.Xaml.UIElement.SetValue(DependencyProperty dp, Object value)
   bei Microsoft.UI.Xaml.NameScope.SetNameScope(DependencyObject dependencyObject, INameScope value)
   bei Uno.Material.WinUI.__Resources._mergedpages_v2_44627d8de4433209f2b1934267892e44_mergedpages_v2RDSC13.Build(Object __ResourceOwner_1)
   bei Uno.Material.WinUI.GlobalStaticResources.ResourceDictionarySingleton__mergedpages_v2_44627d8de4433209f2b1934267892e44.<>c.<Get_54>b__33_1(Object __owner)
   bei Microsoft.UI.Xaml.FrameworkTemplate.Microsoft.UI.Xaml.IFrameworkTemplateInternal.LoadContent()
   bei Microsoft.UI.Xaml.FrameworkTemplatePool.DequeueTemplate(FrameworkTemplate template)
   bei Microsoft.UI.Xaml.FrameworkTemplate.LoadContentCached()
   bei Microsoft.UI.Xaml.Controls.Control.UpdateTemplate()
   bei Microsoft.UI.Xaml.Controls.Control.SetUpdateControlTemplate(Boolean forceUpdate)
   bei Microsoft.UI.Xaml.Controls.Control.ApplyTemplate()
   bei Microsoft.UI.Xaml.Controls.Control.EnsureTemplate()
   bei Microsoft.UI.Xaml.Controls.ContentDialog.<<ShowAsync>b__32_0>d.MoveNext()
   bei Windows.Foundation.AsyncOperation`1.<BuildTaskAsync>d__23.MoveNext()
   bei System.WindowsRuntimeSystemExtensions.<AsTaskCore>d__11`1.MoveNext()
   bei MyUnoApp.Presentation.MainModel.<ShowDialogAsync>d__12.MoveNext() in C:\Users\TKSSonja\Projects\MyUnoApp\MyUnoApp\Presentation\MainModel.cs: Zeile44

  Diese Ausnahme wurde ursprünglich von dieser Aufrufliste ausgelöst:
    [Externer Code]
    MyUnoApp.Presentation.MainModel.ShowDialogAsync() in MainModel.cs

Already checked:
xamlRoot is not null at this time

My calling code:

namespace MyUnoApp.Presentation;

public sealed partial class MainPage : Page
{
    public MainPage()
    {
        Loaded += MainPage_Loaded;
        this.DataContext<MainViewModel>((page, vm) => page
            .NavigationCacheMode(NavigationCacheMode.Required)
            .Background(Theme.Brushes.Background.Default)
            .Content(new Grid()
                .SafeArea(SafeArea.InsetMask.VisibleBounds)
                .RowDefinitions("Auto,*")
                .Children(
                    new NavigationBar().Content(() => vm.Title),
                    new StackPanel()
                        .Grid(row: 1)
                        .HorizontalAlignment(HorizontalAlignment.Center)
                        .VerticalAlignment(VerticalAlignment.Center)
                        .Spacing(16)
                        .Children(
                            new TextBox()
                                .Text(x => x.Binding(() => vm.Name).Mode(BindingMode.TwoWay))
                                .PlaceholderText("Enter your name:"),
                            new Button()
                                .Content("Go to Second Page")
                                .AutomationProperties(automationId: "SecondPageButton")
                                .Command(() => vm.GoToSecond),
                            new Button()
                                .Name(out var GoRightButton)
                                .Content("Let's go right")
                                .AutomationProperties(automationId: "GoRightButton")
                                .Command(() =>vm.ShowDialogAsync) ///<- right here this Task is called
                                ),"

Task Code in MainModel:

public async Task ShowDialogAsync()
{
    try
    {
        ContentDialog dialog = new ContentDialog
        {
            Title = "Some Title",
            Content = "Some Content",
            PrimaryButtonText = "OK",
            XamlRoot = XamlRootService.GetXamlRoot(),
            DefaultButton = ContentDialogButton.Primary
        };

        ContentDialogResult result = await dialog.ShowAsync(); ///<- here it is throwing the exception you see above
        await DialogResult.SetAsync(result switch
        {
            ContentDialogResult.Primary => "OK",
            _ => "Canceled",
        });
    }
    catch (Exception ex)
    {
        Console.WriteLine($"ShowDialogAsync got exception: {ex.Message}");
    }
}

DialogResult Property from Task content is in MainModel:

public IState<string> DialogResult => State<string>.Value(this, () => string.Empty);

In my opinion that should be all fine and working, but somehow it is throwing this exception
Could someone have a look on this and help me what I should change?

Repo link:
https://github.com/DevTKSS/MyUnoApp.git

Possibly related to the mvux pattern thing, so maybe a mvux issue?
#18598 (comment)
Seems to not happen in mvvm

[mikernet]

I don't know why the code above runs on a non-UI thread.

Changing the code above to do this instead:

public async Task ShowDialogAsync()
{
    bool okClicked = false;

    var dialogActions = new DialogAction[]
    {
        new DialogAction("OK") { Action = () => okClicked = true },
        new DialogAction("Cancel"),
    };

    try
    {
        await _navigator.ShowMessageDialogAsync(this, "Some Title", "Some Content", buttons: dialogActions);
    }
    catch (Exception ex)
    {
    }

    if (okClicked)
    {
        await DialogResult.SetAsync("OK");
    }
    else
    {
        await DialogResult.SetAsync("Canceled");
    }
}

Still hits the exception block. Also, SynchronizationContext.Current when the MainModel ctor is executed is null, so it doesn't appear to be running on the UI thread.