I just lost over 30k of exp from completed but not turned in Quests because of this bug, and it woulda made me hit lvl 21 QQ I hope this gets fixed soon.
Besides a few certain quests not being completably such as Practice tree, as speaking with the tree does nothing. There are other quests I've noticed will hang if you accept them and never let out off the interaction screen. This also happens when using the lvl 12 upgrade ticket on a weapon or armor.