Title. I have already killed Leech and Blightstormer and just killed Bramblebrush Cucumberbutt with the Coghammer and it did not register the kill for the challenge.
Yes, I am 100% certain I killed him, as the kill feed showed me killing him and I was the only one alive.
Yes, I am 100% certain that I killed him with the Coghammer.
Challenge still says I did not kill him.