Short Version: Delete the “Cache” folder in your Retail folder.
I just returned after 1.5+ years away (was still 60). I could not access the Rostrum (required 70). Also, I still had the Shadowlands covenant button on my mini map instead of the new DF one. After maintenance today 5/15, nothing had changed.
I read the fix elsewhere, and it worked instantly. Deleted the Cache folder, logged in, and bam - I can now customize my dragons and look at my DF rep status.