Stygian Spires created by Allflame Ember of Abyss don't count for Cross Contamination Challenge

Title. Thought I was being clever to complete this challenge deterministically, but killing a stygian spire spawned from the allflame ember pack (with shrine buff) did NOT count toward the challenge. Later on in the map I encountered a stygian spire that was spawned normally from an actual abyss, and it did count for challenge completion.

Not a huge deal, but this felt like something that should have worked. Also possible that there other monster types spawned by allflame embers that are not properly flagged for other similar interactions.