Thunderfury bug

Hey to the GM´s,
So i did farm all items for the Thunderfury quest. I gone to silithus with my guild and we did summon thet boss.. Everything was good then we killed him.It turned out i cant loot him no one could so he despawned without me getting the quest item he dropped. I hope all the work i put in there isnt just gone like wihtout my reward my thunderfury I did eveyrthing. The item he dropped was the last item for Thunderfury it would have completed it. But it wasnt lootable.
So pls help me i dont want to see me getting nothing after all this work due to a bug.
Here the screeonshot of me dropping it http://imgur.com/pzxaDUL

Ingame name : Taburik

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Something different happening to me, summuned boss= server crashed, leaving me without a boss to fight when i come back online, and the boss isn't resummonable as it shud be. Ingame name: Rendalot