Why can't i finish a kuva lich even I already have correct mods in correct order?

[Crimson578]

https://ibb.co/VBX30pR (sorry, cant find proper way to insert photos) 

its a issue annoyed me for a long time, almost since the kuva lich update been out! as in the photo, i've killed it for many times. and it turn out wasn't dead at all! it still robs my materiel! its really annoying. Is there any ways to help with this?(also, i've report this bug in the "The Old Blood Bug Reporting" post already, and obviously，the bug haven't been solve.)