Cannot start Alliance Quest for Birchus in Garrison

I’m trying to get Birchus for my Garrison but I cannot start Ambassador to the Ancient quest. I’m at Altauur NPC in Gorgrond (49, 49) but he does not offer me Ambassador to the Ancient or Plant Pruning quests. I have not completed either on this toon (at least not the Alliance versions). When I run the Wowhead query to see if I’ve completed these quests, it returns “false”. There might be a bug due to the fact that I have faction changed from Horde to Alliance to Horde to Alliance, etc. Not sure if I started the same quest on Horde or not or what, but I’m stuck and cannot get Birchus.