Holy crap, trying to level my Hordie and got stuck on this, tried everything in this thread with no luck. Ended up doing it all at once.
Stripped naked,
Removed weapon,
Abandoned quest,
Flew away,
Flew back,
Disabled all my addons,
Reloaded,
Picked up quest / item,
/exit out of game,
Logged in and it worked.
I can’t say what aspect of it worked but at least all combined it worked. I’ve seen Blizzard doing fixes on old world content like this lately, wish they’d fix this as well.