Was in a bit of a rush and forgot to add a bunch in the last reply.

What I mentioned earlier is about the keys one can change, but there are the hard-coded Scroll Lock and Print Screen which indeed seem to work a bit oddly for me right now as well.

If I try to use Print Screen, it normally just brings the UI back, but if I first press ctrl or alt (can release or not after) and then Print Screen, it will work, but it's kind of like stuck, too... until I fiddle with other keys a bit...

That might also be due to my keyboard set-up, and I can't re-produce the "Scroll Lock, then press Print Screen and F11" here.

Being as cumbersome and limited as the feature is, I, too, use an alternative. On Linux I have a very simple self-made script to save an image of whatever the active window currently is to a pre-set directory, using the window title as its name and adding time and date to it without any other interaction from me aside from the initial button press.

I might have used Fraps (probably abandoned almost 10 years ago; anyone remember that?) back when I was still using Windows about 12 years ago, but I'd imagine there are plenty to choose from nowadays (like OBS Studio if you only ever want to focus on one window at a time).