Hi!
I'm encountering the same issue!
I've put a display case, put a unique in it (Replica Twyzel) which one my first item out of a voidborn reliquary, and even after logging out, I can't take it out ...
My character is indeed in affliction league and it's the same character that put the item inside the display case.
Display case correctly show Affliction on top but it also has a lock on the upper right of the item.
Honestly, I don't think I'll use the item, but I would be afraid of putting anything in there in the future.
I've seen screen capture where there is at least a destroy button under the item, but I don't have one on my side ...