Had the same problem. Pretty much have to kill them in that section to get the quests drops. If you go into the other room they don't drop but if you pull those in the room outside the doorway, they will drop.
Well i got them to drop, you have to kill them standing on a really specific spot, if you drag them anywhere else and kill them anywhere else they won't drop. Doesn't make much sense to me for it to be this way.