WinUI RenderAsync method doesn't work for making screenshots of WebView2

Description

In WinUI you can call RenderTargetBitmap.RenderAsync(element) to render a screenshot of an element to a bitmap, and then you can save that bitmap somewhere (for example, as a PNG on disk).

When there's a WebView2 in the control tree, the contents of the WebView2 are completely blank, though everything else in the image looks fine.

Version
SDK: Windows App SDK 1.1.5
Runtime: 105.0.1343.33
Framework: WinUI
OS: Win11

Repro Steps

Create a new empty WinUI3 app and put this code in MainWindow.xaml.cs:

    public sealed partial class MainWindow : Window
    {
        WebView2 _wv;
        public MainWindow()
        {
            var b = new Button { Content = new TextBlock { Text = "Do screenshot" } };
            b.Click += OnScreenshotClick;

            _wv = new WebView2 { Source = new Uri("https://bing.com"), Height=400, Width=400 };

            var sp = new StackPanel() { Orientation = Orientation.Vertical };
            sp.Children.Add(b);
            sp.Children.Add(_wv);
            Content = sp;
        }

        private async void OnScreenshotClick(object sender, RoutedEventArgs e)
        {
            var rootPath = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments);
            await CaptureAsync(Content, Path.Combine(rootPath, "WindowContent.png"));
            await CaptureAsync(_wv, Path.Combine(rootPath, "WebView.png"));

            var messageDialog = new MessageDialog($"Screenshots saved to: {rootPath}");
            messageDialog.Commands.Add(new UICommand("OK"));
            InitializeWithWindow.Initialize(messageDialog, WindowNative.GetWindowHandle(this));
            await messageDialog.ShowAsync();
        }

        public static async Task CaptureAsync(UIElement element, string destination)
        {
            var bmp = new RenderTargetBitmap();

            await bmp.RenderAsync(element);

            // get the view information first
            var width = bmp.PixelWidth;
            var height = bmp.PixelHeight;

            // then potentially move to a different thread
            var pixels = await bmp.GetPixelsAsync();

            using FileStream fileStream = new FileStream(destination, FileMode.Create);

            var ms = fileStream.AsRandomAccessStream();

            var encoder = await BitmapEncoder.CreateAsync(BitmapEncoder.PngEncoderId, ms);
            encoder.SetPixelData(BitmapPixelFormat.Bgra8, BitmapAlphaMode.Ignore, (uint)width, (uint)height, 96, 96, pixels.ToArray());
            await encoder.FlushAsync();
        }
    }

And then run the app, and click the button in the app.

On my machine it produces two screenshots:

1. Just the WebView2 (blank rectangle):
   
2. The whole app's main window's contents, which has content, except for the blank WebView2 (valid screenshot, except bottom right is blank gray rectangle):
   

Originally reported in .NET MAUI: https://github.com/dotnet/maui/issues/9718

AB#41360109