I was with one other live person and 2 bots, on recruit against the grain set to private so we didn’t get any interuptions. I was obviously grail knight my friend was playing zealot. Chaos Spawn walks right out of the gate, get my three riposts really quickly and keep dodging, boss dies. I get the system message that I have to finish the level to complete the achievement. We did easily and I did not get the achievement.
It shouldn’t matter but my friend was the host.