Are you running in fullscreen or borderless fullscreen? I have seen other people have problems running fullscreen exclusive, rather than windowed borderless. It had to do with alt-tabbing, rather than screenshots, but I’ve seen this in another game.
I don’t have this problem with CDDA, but I have this exact problem with FTL. If I run FTL windowed I can get a screenshot of the game, but if I run the game fullscreen I just get a screenshot of my desktop. Not sure why, because I used to be able to get screenshots through Raptor AMD gaming evolved app when I first built my PC a couple years ago no problem. Now I cant record or take screenshots of FTL unless it’s windowed, for some reason.
Also, try alt+prntscrn to get a cap of whatever window your mouse is on(if you have multiple windows/screens open). Theres also win+prntscrn, but that would probably just do the same as your getting now, unless it’s windowed.
Just woke up, still drinking my first cup, hopefully the above is legible enough.