Ran 4, one was HOA and it didn’t count so I’m 3/4.
The wording for the quest says “Complete 4 dungeons on Mythic difficulty” not “Complete 4 dungeons from the current expansion/season on mythic difficulty”.
So I guess I have to avoid the non TWW like the plague.
My other three were:
Dawnbreaker
Ecodome
Ara kara