Bone collossus fight ended with no drops

Bug Report ID: #2526184915

I just killed the dual boss of Sulfuric Caverns (one is bone collosus, I don't know what the other boss's name is), no drops, and the boss attacks have not ended despite both bosses are dead and the game registered the map as complete.

It may have something to do with being killed simultaneously, or close to simultaneous and flags are not being set properly.