In my case....
Album Artist on the vehicle screen is fine, Folder Hierarchy is not; they are about the same thing. I have 2 music main directories, Classical (500 folders) and Pop (1000 folders), flac, which I bought over 40 years. I don't want to be looking through Classical when I want to play Pop. So I use the Folder Hierarchy, nothing else. The vehicles built in music player does not have a problem, it shows all of the music folder hierarchy.
Poweramp's Android Auto listings have a A-Z icon which brings up a A-Z keyboard. When H is pressed, it jumps to the folders starting with H. It is so so much better than scrolling. I do not change music when driving, I stop often enough, it is easy to avoid.
I tried resetting the vehicles Sync 3, the problem persists.
Thanks,