Yeah, the questline is widely known as very buggy amongst the 19 community, and it is known by GMs aswell. As far as I know, GMs have also given instructions to complete the bugged quest for you if they get a ticket concerning it. Well, at least they completed it for me
I did it on my hunter like a week ago and it worked perfectly fine, though. It's just about luck if it bugs or doesn't.
You do not need help from a GM contrary to popular belief. To the Rescue! - Quest - World of Warcraft. The top rated comment with the steps about taking of your gear and such works great. Your welcome.
When I did it I had the same problem, solved it by just doing some other quests from the same place. Any of the quests must have had any impact on the needed quest.