ContentDialog not visible if background is set to transparent

Describe the bug

When you have a FluentWindow object and set AllowTransparency to true and background to transparent and show a ContentDialog this ContentDialog won't be visible

To Reproduce

Code:

            FluentWindow window = new();
            window.Content = new ContentPresenter();
            window.AllowsTransparency = true;
            window.Background = Brushes.Transparent;
            ContentDialog contentDialog = new((ContentPresenter)window.Content);
            contentDialog.Title = "Save hashes to ... file(s)?";
            contentDialog.PrimaryButtonText = "Multiple";
            contentDialog.SecondaryButtonText = "Single";
            window.Width = 0;
            window.Height = 0;
            window.WindowStartupLocation = WindowStartupLocation.CenterScreen;
            try
            {
                window.Show();
            }
            catch (InvalidOperationException)
            {
                // Ignore
            }

            window.Focus();
            window.Activate();
            contentDialog.ShowAsync().ContinueWith((task) =>
            {
                // ...
            }

Expected behavior

The content dialog shows in front of a transparent window.

Screenshots

No response

OS version

26040.1000

.NET version

.NET 8

WPF-UI NuGet version

3.0.0-preview.13

Additional context

No response

Start by reproducing the issue with FluentWindow, AllowTransparency, a transparent Background, and ContentDialog.ShowAsync using the code in the report. Trace how the dialog is displayed when the window is transparent; done means the ContentDialog is visible in front of the transparent window without breaking the reported setup.