There's a quest called 'Repairing the Phial', as in the 'White Phial' from that apothecarys apprentice. He wants you to get him three items, one of them is a Briar Heart. I am on this quest but unable to finish it because I can't loot the Briar Heart from the assigned questmob (he's dead in that Forsworn-camp) but he hasn't got any heart on him that's lootable.
Currently I'm walking around with like 8x Briar Heart, can't sell or store it because it "counts as the questitem" but since it wasn't correctly looted from assigned questmob, I "haven't got the right one", so basically is just massive bugging.
Got quite a few quests that are bugged.
edit: My guess is that you're on this quest?