Just a warning for people since this bug seems to have hit me.
A lot of the tasks/missions/Hero rewards give a signifigant XP bonus plus X AA.
If you are on 100 percent AA you will get the AA bonus but the Level XP is completely wasted.
Example: My monk and my shaman complete something with a reward of 4 AA and 5% of level experience.
Shaman who is on 100 percent level gets 5% of a level and 4 bonus AA.
Monk who is on 100 percent AA gets 0% of a level and 4 bonus AA.
I have also HEARD that fellowship sharing can rob you of the level bonus but can not confirm that.