I am not sure what to say about this issue but …
When you go hand in NPC you sometimes can’t talk to the NPC you have to move away for some stupid reason why on earth is this happening not just that but after you have handed in the quest and try to take a new quest you can’t talk the Npc so you have to move away and then respeak to her don’t matter if you have an auto quest on or not the same issue
Also when in a group why doesn’t quest count towards both people in the group it’s kinda stupid that it does not other xpacs it has counted so why now it dont???
This has been an issue for me for ages now, I’ve just got used to having to move a little bit away before returning to whatever NPC I need to speak with.
I have had this bug for years on and off and my trick is to mount up on my yak and open up the vendor after that you can click the npc properly and talk to them for the next quest or hand in. Any vendor will do if there is any close by. Doing that seems to brake whatever gets you stuck