Mastadon Tusks not dropping.

I always kill the necromancer first and then the mastadon, this run i had devouring diadem on which I assume was consuming the corpse of the necromancer and preventing the drop from appearing.
Killed mastadon first and then I dropped the tusks no problem.

Can confirm -- Tusk doesn't drop. I am also using the Diadem mask but found that the tusk DOES drop if you kill mastodon first. Tested on different characters, all wearing Diadem. Hopefully it gets fixed soon, but for now that's the "fix".