I had this issue until I manually selected my logged-in instance from the dropdown list at the top of the main screen.

Same. Symfonium has the most polish of the subsonic apps I tried. Don't miss Spotify at all.

Are you using the warwickh Kodi plugin? It's been working pretty well for me.

Sticking with Sonixd for desktop for now but watching the development of Feishin (MPV).

Symfonium (Android) and Sonixd (Windows) to stream from my self-hosted Navidrome server. Has worked great for me with my 35k song library.