I don’t know if I haven’t met the prerequisites or not, but the Class Hall Mount quest is not available to pick up nor did I pick it up in the past. I unlocked all of my artifact traits prior to BFA. Are Class Hall Mounts still available or are they legacy achievements like the Armani War Bear? The War Bear is not available anymore and am comparing this situation to that mount. Sorry for the noob questions.
They are still available. They require you to have completed the entire Legionfall campaign - specifically the achievement Breaching the Tomb:
on the character in question.
Once you have completed that achievement, a quest will appear in the Legionfall area (over near where the Command Centre is when it is up) sending you back to your class hall to start the scenario to get your mount.
I just got the Breaching the Tomb achievement this afternoon on my paladin, but am unable to see any quest to start the mount questline at the known questgiver. I obviously have the class hall campaign done as it’s needed to get the legionfall campaign stuff finished. So personally I am not sure if it is still truly available.
Did you check back at the starting camp on Broken Shore? That’s typically where the quest givers should be (that was where both my druid and DH class mount quests started). I’m pretty sure there would be an announcement if Blizz was retiring class mounts, and I got my DH class mount just last November.
I just did it and I had the same confusion until I figured out I what I missed. Finish all Armies of Legionfall and the Broken shore quest in the class hall