Act 2 Bone pit Boss sometimes does not drop its quest item.

Happened to me twice on my Lich. First time during normal mode and now a second time during Cruel play through. Creating a new instance and killing it a second time gave me the rewards in normal. I haven't killed it a second time in cruel yet since it just happened again. But if it fails to drop after an instance reset I will make another post in this thread.

Edit: It dropped on the second kill again