Rare finisher effect not working

Im playing a monk and none of the rare finishers effects are working at all, however when i switch to another character they seem to work. i dont understand why they work on one and not on the other. i have unselected all effects on the character that works but they still wont work on the character im currently playing. i have tried removing the filter, verifying game files and even changing visual settings but no luck please help.

This is what I got from them:

Additionally, if you are destroying the corpses of the rare monsters, the finisher effect will not activate - is it the case that your build may be doing this (shattered enemies, enemies exploding etc)?

It feels like we got scammed. How does it make sense that it only works if the monster leaves a corpse after being killed?