Opening system menu using Alt+Space stops a content dialog responding to mouse clicks

Describe the bug

Opening the system menu using Alt+Space stops a content dialog responding to mouse clicks. Fortunately it still responds to the keyboard. Opening the system menu by right clicking on the caption seems to work ok.

Steps to reproduce the bug

1. Build and run the attached repro project
2. Click on the "Open content dialog" button
3. Type Alt+Space to open the system menu
4. Click in the window to dismiss the system menu
5. Attempt to close the content dialog by clicking it's OK button

AltSpaceIssue.zip

Expected behavior

The mouse should work.

Screenshots

https://github.com/microsoft/microsoft-ui-xaml/assets/28826959/4be4e49a-ad55-4f12-a84b-efa62f34cbf8

NuGet package version

WinUI 3 - Windows App SDK 1.4.1: 1.4.230913002

Windows version

Windows 11 (22H2): Build 22621

Additional context

The repro project also contains a work around which involves subclassing the window, but it shouldn't be necessary.