there is an outline that appears around MC. I hope I am not making that last part up.
Yes, I made that part up. What I was thinking about is this:
When MC won't let another window appear, the line under the folder symbol in the 'file explorer' taskbar button turns red. It is typically grey or blue.
I can reproduce the full screen issue. It happens every time I do the following:
Have a video playing in standard mode playing now (no issues here with bringing up other windows).
Then double click the playing video to make it full screen. Double click playing video again to get back to standard mode.
Now no other window will appear above MC. The 'File Explorer' taskbar button has a red line.
I tested with videos on my desktop using JRVR and Red October HQ, on NUC8 windows 11.
I get the same results on my alienware laptop. On that one the 'file explorer' taskbar button flashes red, which I must have seen before, hence my earlier comment about an outline appearing.