Hey Grey!
Sorry to hear about that. In my preliminary testing around this, I am seeing the DoT removed. Is it possible you were hit by another Nazeebo Auto-attack after using Last Laugh?
Either way, if you could be so kind as to forward that replay, along with a time stamp, to us following the steps on this post, I will be more than happy to look into that!
Huginncord, Heroes QA Extraordinaire