WinUI 3 controls in Simple Island App are invisible until focused

[litherum]

Building and running the unmodified Simple Island App project results in a window that looks like this:

However, there are suposed to be WinUI 3 controls on the top and bottom of the WebView2. The XAML has:

    <Grid Padding="10">
        <Grid.RowDefinitions>
            <RowDefinition Height="50"/>
            <RowDefinition Height="*"/>
            <RowDefinition Height="50"/>
        </Grid.RowDefinitions>
        <StackPanel Orientation="Horizontal" Grid.Row="0">
            <Button x:Name="Button" Click="ClickHandler">Click Me</Button>
            <TextBox Text="Text goes here" Margin="10" />
        </StackPanel>
        <WebView2 Grid.Row="1" Source="http://bing.com" />
        <Button Grid.Row="2">Last Button</Button>
    </Grid>

So there are supposed to be a Button and TextBox above the WebView2, and another Button below it.

If you click where the TextBox control is supposed to be, it shows up:

But then if you click away from it, it disappears again.

I'm using Windows 11 23H2, Windows 11 SDK 10.0.22000.0, Visual Studio 17.8.1, and Windows App SDK 1.4.3 (1.4.231115000).

[edward-a]

I suppose i am pretty late to add to this issue. Anyway, I stumbled upon this as well and as it appears the reason for that is the Windows' dark theme that makes controls' background transparent. So, i guess that's by design and the fix is to make the background behind controls dark.