PoE2 Stuck in Act 2 "a theft of ivory"

Apperently i'm stuck in act 2 with the quest "A theft of ivory" where i need to collect the Mastodon tusk. It is dropped from one of a double bosses a the end of the quest but even after killing them many times and in different order the tusk won't drop. Am i missing something obvious or is it a bug?

#Thanks in advance
MLG