@WiiM Support,
What one hand giveth the other taketh away!
The Android app has just updated and this week it works for AssetUPnP and not MinimServer! I bet if you used the iOS app to browse AssetUPnP it'll list the AlbumArtist tag in the track listing.
The underlying problem is that when the server sends track metadata to the WHA, instead of picking the non-AlbumArtist tag the Android app used to pick the first and the iOS picked the last. This means that for some servers it worked whilst others it didn't.
<upnp:artist>Marvin Gaye, Tammi Terrell</upnp:artist>
<upnp:artist role="AlbumArtist">Various Artists</upnp:artist>
Now the Android app picks the last, and I'd bet iOS picks the first!
I guess I'll update my existing open ticket to alert them to this.