Sulphuric Cavern boss loot is bugged

Twice now i have fought the sulphuric caven boss and only gotten blue loot. Not even waystones which i thought was mandatory for bosses.

The last one i did was a tier 16 with irradiated and corruption on it. So blues seems kinda meh...

Could you please look into this?


Update: Dont know if this matters, but i just did another one where i killed the big monster last. I got loot this time, so can it be the order you kill them thats the problem?