I’ve reported this in-game multiple times without it being fixed, so bringing it to the forums.
Vol’Dun quest ‘A Strange Delivery’ at the end of the Port of Zem’Lan storyline (Horde side) requires the player to turn in an object to Rhan’Ka at the Goldtusk Inn.
The Goldtusk Inn has a progressive questline that ends in it becoming a fully functioning in with merchants. It goes through multiple phases as the player progresses in the quests. In the final phase, the version of Rhan’Ka that spawns is not a valid turn-in NPC for ‘A Strange Delivery’.
So, if a player completes the Goldtusk inn questline before starting Port of Zem’lan, it is impossible to turn in ‘A Strange Delivery’.
Should be a quick fix. Just check the NPC id# for Rhan’Ka in the final phase and update ‘A Strange Delivery’ to include that id as a valid turn-in NPC.