Windows 11 tramples over Server 2019 ‘StuckRects3’ value causing all Win 10 system icons to be hidden if this setting roams. # Resetting this key at Windows 10 login ensures all the expected Win 10 system icons are displayed.

You have to close explorer before you whipe the registry key or explorer.exe writes back the old settings on exit.

If you open cmd.exe then run these commands line by line , it will log off then when you log back in the Clock will be there ( Until you log back into AVD which you will have to do again )

taskkill /IM explorer.exe /F
reg delete "HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\StuckRects3" /f
shutdown /l