I just finished Episode 3 of The Ultimate Doom - the BFG Edition. The achievements in Galaxy were working just fine so far, but turns out it may be the only one that's not popping up after I killed the Spider Mastermind. I tried unlocking another achievement on Doom II (one involving finding a secret) and it just worked.

This is supposed to work the same way as Steam achievements. as I just finished three episodes in Ultra-Violence. (Minimum requirement is finishing the episode in Hurt Me Plenty or above as with the other two). I even saved my progress on the other two episodes and yet when finishing the last mission, it unlocked the achievements for each one of them.

Having said all that, here's my questions to whom may concern: Have anyone encountered this issue? And how can I solve it?

I'm going to try replaying Episode 3 in Ultra-Violence, as I'm aiming for the Rampage achievement here.

Thanks in advance!

P.S.: And before you ask, I deleted the "gameplay.db" before trying unlocking achievements again. That's how I unlocked one for Doom II and yet I can't for Doom Episode 3.

Update (18:02 UTC): Played Episode 3 again and no luck. It's not registering the achievement. I really need your help.

Update (2017-09-22 18:31 UTC): Interesting... I managed to unlock the Episode 4 and Rampage achievements. Considering I also finished Episode 3, the system recognized I finished all four episodes on the Ultimate Doom. It should've unlocked the E3 achievement, but it seems to be glitched/bugged on GOG.