With Windows 11 21H2 22000.527, if taskbar is set to auto-hide and Start11 is running and the position of the taskbar is at the top of the screen, then the taskbar may not hide correctly, leaving a dark bar close to the top of the screen, and even when open, will not snap to the top of teh screen but about 10 pixels below it.
In the excerpts below, the left one shows the very top left-hand corner of the screen with the taskbar allegedly hidden, and the right one shows the taskbar shown at the same part of the screen.


Ideas?
Addition: the start menu will not show at all (the picture on the right shows the situation after the Windows key is pressed). Only the taskbar will appear. If I type in the start menu, the result is

after I have typed FIREF to get Firefox. That is, the result is that only half of the start menu is shown.