Doing hunters for raid in Dragonscale Hills and have killed Delilah Windrider twice and no one got credit for the kill including myself.
Make sure named aren't destructing on DS or other non damage sources or else you don't get kill credit or loot (this is for anything). I just did DSH and it updated, its not bugged. Also make sure you are clicking between different achievements or else the current selected one doesn't refresh.