Hey there @KriHavok!
We would recommend this:
Impact: Impairs Functionality
Category: Quests
Sub-Category: NPC & monster
That said, while we don't want to make it sound like the category isn't important, a reported bug in the wrong category is more helpful than not reporting it at all. We read each and every bug report, so we'll be happy to re-categorize it on our end if need be.
Thanks for bringing this to our attention!