Why do I not get the 'Overachiever' achievement?
To get the first star in the 'Overachiever' achievement, you have to get 50 XP in a day. However, in my case, even if I do get 50XP or even more, I still do not get the achievement... Is this because there is a bug or am I doing something wrong and therefore unable to get the achievement?
Maybe it's because you're testing out of skills. Otherwise, I'm not quite sure.
I've gotten it no problem. Sounds like a bug you need to report.
You only get every achievement once. Once you have it, it unlocks the next level and you need more XP for the second star.