I just did BFD and killed Kelris. When he died people lit all of the braizers and caused a wipe. When I got back the corpse was not there and I could not loot the quest iteam. If you want to see that I was actually there and the chat log you should be able to see it at http://www.twitch.tv/RecSverkerman. He was streaming it and you just have to see his past broadcast.
This took place at 2015-03-03 ~14.45 I would guess
Ingame name: Kallemera
Would very much appreciate if you could send me the Head. And yes, game masters should send iteams that were lost like this, I had a similiar experience on retail in MoP. Afterall, this is supposed to be blizzlike right?