Xbox - getting achievements without completing the tasks

why_do_it_do

I was afk just before pressing y to begin finding a game. The killer I had picked was demogorgon and I do not have the singularity unlocked. Whilst afk I randomly got the achievement "Complete the Evolution". I also recently got the achievement III-50 without levelling a character passed that point, however I believe that's because the achievement was added since I was last on the game so loading back onto the game made it realise I should have the achievement.