So I just finished The Chest for the first time, and I was using Cain. I got the "Dad's Key" achievement, which I guess you get the first time you complete it with any character.
But for some reason, even though I got the "Cain's Eye" secret unlock, I got the "???'s Soul" achievement. So the game thought I completed it with Cain, but Steam thought I completed it with ???. Question now is; who the hell should I use to unlock the "Cain's Eye" achievement? ??? or Cain? Is this a common bug, or did my game have a seizure?