ATO II - Item Quest Bug

While wearing The Devouring Diadem Wicker Tiara once you kill one of the bosses Ekbab to drop the Mastodon Tusk and the corpse is consumed the item quest doesn't drop.
I killed 2/3x and it didnt dropped. I had to take off the helmet to drop the item.

Bumping for the exact same cause. Was wearing devouring diadem and tusks did not drop for quest. Quest item dropped only after switching head gear and redoing boss fight.