I just discovered this glitch in my game.
I play a vanilla game with no mods or anything but since I patched to 1.50 my sims teens ( who are signed up for after school activities) will go there and suddenly I get all of these pop ups that they have mastered their skills. Example: my teen went to his first art club after school activity and while he was there I got notices that his sculpting and painting skills were mastered?! He only had one painting skill and no sculpting skills.
I don't know if this has happened to anyone else but I am very bummed about it.