Are you actually speaking to the right npc? You have to speak to Swift at the Hall of Flames to get the initial quest that unlocks the amal'jaa quests - I'm not sure but I think the Ixal quests require you to have gotten maximum rank in the other beast tribes before you can unlock it. You also need to have passed a certain quest in the main scenario, but as you've completed Heavensward that is pretty moot.