"Spawn" essence monster drops no essences

In the unique map Whakawairua Tuahu there are natural Spawn enemies. I believe it's the only place in the game where they appear without being summoned. I had the misfortune of having one of them get picked to be an Essence monster around about where I am in the screenshot.
When I released it, it used its suicide skill and didn't drop any items, including the essences on it. It's normal behaviour for monsters to not drop items when they suicide, but it would be nice if they still dropped their essences.

Might also be worth looking at Alira's Martyrs, because they share the behaviour.

Screenshot with bug report number, not really much to show


Edit: For clarity, Spawn are those red suicide squids.