I can't unlock all Galaxy achievements in Trine 3, GoG client says that i have 65%, it stopped unlocking after finishing chapter 5, but i have them all in game. I tried to play some chapters again but it doesn't help in any way?
Do you know any way to fix it?

I have 0% unlocked in GoG client, but I have like 7 achievements unlocked in-game menu. I dunno looks like some like me and you and others have this issue with achievements not unlocking in GoG Client. Guess no one really cares about us and this game anymore. =(

Maybe try re-install the client or game or both. Dunno tried to reinstall the game still will not unlock, maybe the problem is with the client itself.