I've found that when I loot something and I want to pull it down to the quick slot bar, the item won't move/drag.
This also happens when trying to drag a weapon onto you character.
I've been able to 'fix' this by escaping my inventory and going back to the play field, then open up the inventory again...usually after 2 or 3 times of doing this, I'm able to again drag items around.
Not a super bug, but it's annoying when it happens.
