Night Fae covenant switch broken

I switched to Night Fae, but can’t complete the quest “The first new growth”. I already completed the quest “Flutterback”, but the Night Fae sanctum upgrade vendor, Zayhad, doesn’t even offer the option to view the covenant. The covenant is now completely broken for me, I can’t proceed on the sanctum upgrades, or get the quest to get my covenant DPS ability. Relogging, re-taking the quest or leaving the zone doesn’t help.

I’ve now made 4 tickets about this, and only getting the most useless responses, suggesting “fixes” that I already mentioned I tried, making it very clear that they don’t even read my tickets. The last GM suggest I make a forum post right here, or a bug report, but neither actually fixes the bug.

If this isn’t fixed before 9.2 I’m screwed because I can’t use my covenant of choice. You have broken my character and are refusing to assist me.

EDIT: Eventually I got this quest unbugged by completing more campaign quests. I tried various questlines like Shandris quests to rescue Tyrande, Bwonsamdi’s quests to battle against Muehzala, but I think doing the quests for the theater (starting with “Breaking a leg”) was the only thing I really needed to do to get my covenant in a working state: they lead to getting your DPS spell (for me as a warlock that’s Soul Rot), and the subsequent quests are about improving your sanctum.
Totally unclear, at least for me and 4 GMs who did their best not to read the information provided in my tickets. This may be the first time I’m dissatisfied with Blizzard’s customer support, but it was REALLY bad.

You may have more luck if you post this in the correct forum. Your issue is not a launcher app bug.