Critter Den

I accepted the quest of stirring den, destroyed it after roughly 10 seconds, quest showed that I have to kill 2 remaining critters, but only one was visible. I killed it and quest still said "1 remaining", but there was no icon of it anywhere, sound or visible critter. So the quest failed.

"Kill 1 remaining critters" and no critters around.

Critter should be visible and killable, but the critter was nowhere to be found.