At first, the items stopped dropping when I was at 3/4 and then I read on https://www.wowhead.com/quest=63757/looting-the-looters that I should abandon the quest and re-start it, which I did.
However it didn’t help, I got to 2/4 and items stopped dropping again.
I re-abandoned it and re-took it but now I am getting the items (got screenshots from looted items) but the quest doesn’t progress, I am stuck at 0/4 and trust me, I have re-taken it few times already.
Just to add another voice… same issue and I don’t think the drop rate is the issue here. Had a series of issues with this quest.
Quest did not “activate” when I hit accept on the pop-up dialog. Didn’t realise until I had completed and handed in the two other quests that “Kah-Than” gives you (Last Place You Look & Rescue from Torment). Not sure if this is related the quest breaking for me (I’ve successfully completed on 6 or 7 other chars so far without the problem).
When I did realise the quest had not activated, I activated it but Kah-Than did not appear or follow me around. From memory, he did not reappear until after I left the area and returned. I THINK he needs to be present for the quest to proceed (not 100% … but, again, just listing things that did not play out as with other characters). After I did get him to spawn, he would periodically despawn even if I did not leave the area.
Even when Kah-Than was present, I was not getting any drops / updates on the quest. Deleted and tried again… got 2 of 4 in about 5 minutes… and then stopped again. After another 20+ minutes, I decided to try again on a different day (thinking perhaps a WQ was causing me to hit phasing or something). On return, no change.
Opened a ticket and worked through a few back & forth with support. They had me delete the quest and try again… still no luck. This time I got to 1 of 4 in the first couple of kills and then all progress stopped (I estimate I killed at least 50 mawsworn in the designated area with no drop).
As mentioned, I’ve completed the quest multiple times on other chars and am able to easily complete the quest while I am finishing the other two quests in the series… so, if it is working correctly, I don’t think the drop rate is the root issue.
One other thing I noticed is that, after I deleted the quest the second time (having collected 2 of 4 before deleting) when I got the one drop I did get, Kah-Than said the normally gives when you get 3 of 4 (something to the effect of “Actually, that item does have a use, but it has no value to us.” or something like that). If the quest had correctly deleted before… shouldn’t I have gotten the first line he says instead? (Basically he dismisses the first “drop” as garbage).
Hope that helps. My ticket is still open and I submitted a bug report as well.