TextBox ContextFlyout with custom options doesn't show if no text is in clipboard

Describe the bug When custom actions are added to the ContextFlyout on the TextBox control, the flyout quickly shows then disappears if there is no text in the clipboard and nothing in the Undo stack. Sometimes it doesn’t show at all.

Steps to reproduce the bug

1. Have empty or non-text data in your clipboard.
2. Right click in the TextBox
3. ContextFlyout shows briefly then disappears

Expected behavior The flyout should show if there are custom actions like the code sample below. If there are no custom actions, the flyout should not show at all, even briefly.

Version Info NuGet package version: [Microsoft.UI.Xaml 2.4.2]

Windows 10 version	Saw the problem?
May 2020 Update (19041)	Yes

Device form factor	Saw the problem?
Desktop	Yes

Additional context Example code to reproduce the behavior in a new UWP app XAML:

<TextBox x:Name="tb" Loaded="tbloaded" Unloaded="tbunloaded"/>

C#:

private void tbloaded(object sender, RoutedEventArgs e)
{
    tb.ContextFlyout.Opening += ContextFlyout_Opening;
}

private void tbunloaded(object sender, RoutedEventArgs e)
{
    tb.ContextFlyout.Opening -= ContextFlyout_Opening;
}

private void ContextFlyout_Opening(object sender, object e)
{
    var flyout = (sender as CommandBarFlyout);
    flyout.PrimaryCommands.Add(new AppBarButton()
    {
        Command = new StandardUICommand(StandardUICommandKind.Close) //Just used as an example, doesn't matter what the UICommand is. Behavior is the same
    });
}

[ranjeshj]

We don’t need to fix this in WinUI3. In WinUI3 we are using MUXC one.

[chingucoding]

Does the WinUI 3 use the MUXC contextflyout or is it using the WUXC one? Would you like me to create the tracking issue?