Sometimes essence monster drops nothing

I've occasionally had Essence monsters drop nothing, no essences and no other loot. It seems more likely to appear when the Essence monster is the last rare monster in a map with no boss.

I want to add that I am on PC and also have encountered this. And its not just when its the last rare, checked my item filters and turned them off as well and still occasionally run into it. I know there are drop tables and its rolled to see if its a regular or greater essence, but its almost like it rolls a 0 and drops nothing.

And if there is a monster that can sacrifice itself or other monsters it can also remove all drops from an essence monster, I think. I have had this happen in the temple of kopec a few times.