achievement BUG,Ozma's Past Unable to unlock.THE FIRST BERSTERKER achievement Completed.

[背课文的吸尘器]

achievement BUG,Ozma's Past Unable to unlock.THE FIRST BERSTERKER achievement Completed.

[(MNK)_Fat_poney]

Same here, Ozma's past didnt unlock although I have all 15 collectibles. I chose the right dialogue and was able to kill the Ozma with 3 phases 3 times now but it also locked me out of the true ending achievement and finishing the game in normal and easy mode achievements.
I have the no summon and ng+ achievement.

That really sucks, I have never had so many issues with achievement on a game on steam.