NavigationView throws threading error when used in new window

Describe the bug

As of WinUi 2.5, NavigationView throws the following error when used in a separate UWP window: The application called an interface that was marshalled for a different thread.

Steps to reproduce the bug

Steps to reproduce the behavior:

1. Create UWP app
2. Add NavigationView to main page
3. Create new page with a NavigationView
4. Add code to launch a new window, and navigate to that frame. (See example below)
5. Launch the app and run code to open the new window
6. See error

Window launch code example:

CoreApplicationView newWindow = CoreApplication.CreateNewView();
ApplicationView newView = null;
await newWindow.Dispatcher.RunAsync(CoreDispatcherPriority.Normal, () =>
{
  Frame frame = new Frame();
  frame.Navigate(typeof(NewPage), null, new SuppressNavigationTransitionInfo());
  Window.Current.Content = frame;
  Window.Current.Activate();

  newView = ApplicationView.GetForCurrentView();
  newWindow.TitleBar.ExtendViewIntoTitleBar = true;
});
bool viewShown = await ApplicationViewSwitcher.TryShowAsStandaloneAsync(newView.Id);

Expected behavior

The navigation view should work in a separate window.

Screenshots

Version Info

NuGet package version: [Microsoft.UI.Xaml 2.5.0]

Windows app type:

UWP	Win32
Yes	?

Windows 10 version	Saw the problem?
Insider Build (21277.1000)	yes
May 2020 Update (19041)	Yes
November 2019 Update (18363)
May 2019 Update (18362)
October 2018 Update (17763)
April 2018 Update (17134)
Fall Creators Update (16299)
Creators Update (15063)

Device form factor	Saw the problem?
Desktop	Yes
Xbox	?
Surface Hub	?
IoT	?

Additional context

This bug was discovered here

Edit: fixed package version

[tsvietOK]

@ranjeshj TestApp.zip

[winston-de]

I can’t repro the issue anymore either. Since the issue seems to be solved, closing. Thanks for the fix! 😄