Yeah, achievements seem to be bugged for me too. I got like 7 of them and then none of them unlocked anymore.
Interestingly, when I unlock an achievement in-game now, it's displayed correctly on the in-game achievements screen, but doesn't unlock in Galaxy. If I then leave the game and start it again via Galaxy, the in-game achievements screen only shows those achievements I've previously unlocked in Galaxy - not the ones that unlocked in-game and failed to unlock in Galaxy.
I unlocked my most recent achievement on 30 September - the same day updates 1.0.1 and 1.0.1b dropped. So I think it might be possible that those updates broke achievements, either in general or just for my current playthrough (since I started that playthrough on 1.0.0, maybe something got mixed up).
I don't really care for achievements, but I really hope unlocking in-game achievements doesn't have some sort of impact on the game, like unlocking a "true ending" or something like that. That would be pretty unfortunate...