Hello all, so when I played the game on Normal difficulty I noticed that achievements didn't pop up anymore even if I theoretically obtained them. I have achievements for all bosses BUT for the Episode 3 one, for example. I noticed that I had the NVIDIA GeForce overlay active at that point, so I deactivated it and from that point onwards the achievements were fine.

...until today. I actually unlocked the Achievement for buying 10 upgrades earlier, but now I'm replaying E3M1 which contains one of the "easter egg characters" achievements. And it doesn't pop up when I find the guy. Nothing. I've tried restarting the game, playing single stage mode... nothing seems to work. What could I do? I checked the GeForce overlay and it's still inactive, as it is since I've disabled it.

Maybe achievements only unlock when playing the campaign mode and not the single stage. I don't know if that is the case as I unlocked almost all of them playing the campaign.

About the missing pop up: have you checked if Overlay options for GOG Galaxy (Settings > Features) are active?

Yes, Overlay and Achievements options are all checked and in fact I had no problem before when unlocking the other one. I even added GOG files to the antivirus's exception list as stated in the GOG FAQs but it still don't seem to work. I don't really know if it's an issue with this specific achievement (Too Serious) or not. I guess I could proceed in the game and see if I unlock any other I'm missing, but I would be pretty annoyed if I completed Hardcore mode and the achievement didn't pop up for that. Wouldn't be the end of the world, but definitely annoying.

Now everything is all right. I literally have no idea at this point why achievements would sometimes not trigger but whatever, I'll keep playing my hardcore run hoping the game decides not to do any funny stuff should I beat it lol