The only recurring bugs for me are with Unload. Half of the time I use Unload the animation just continues going after the effect is done. Also since the latest patch sometimes when I click Unload the bar starts to "channel" and the animation happens but no damage is actually happening...shortly after I can recast it again as normal.
I can't remember what quest it was (or if it was a Bounty Hunter quest or just a normal quest) but I did have one quest mob that I could not damage at all. He killed me and when I respawned I beat him easily.