Lost quest item drop

I am on the "A Theft of Ivory" Mission. I killed the bosses twice to recieve the tusks. I thought i obtained them killing them the first time, logged off for the night and saw the quest was still there. I am unsure if I had turned the quest in before logging off but after logging back on I have no tusk in my inventory and the boss won't drop it.

Reference ID #: 2,834,120,975