Grimlock: I tried with two games, CrossCode and XCOM enemy within, and the screenshots worked.
The only anormal thing was that the first time I tried to do the screenshot with CrossCode an error appeared ("Screenshot failed to be saved" or something like that) after that it seems that everything works.

TerriblePurpose: F12 no longer works. It leaves a temp file in the screenshot folder, but nothing you can access and no actual screenshot. Sometimes it freezes the game as well so I have to CTRL+ALT+DEL and kill the game process. This while playing No Man's Sky. Haven't tried other games (actually only just thought of it), so not sure if it's game-specific. I'll try some other games tonight and report back if there's any difference.

Nostalgiaheavy101: I think the bigger issue is that uploads of screenshots have to be less than 1MB in size (particularly a .jpeg / .jpg file). I just uploaded some screenshots to my activity profile page and that's why it was not uploading a few of them. IMHO, could function a whole lot better because lots of people like to take screenshots of their games to share to friends. <3