Just out of curiosity, have you checked out Airsonic
https://airsonic.github.io/? It's a fork of a fork (fork of Subsonic to Libresonic, fork of Libresonic to Airsonic). I'd be curious to see if the problem exists there.
The reason I mention it is that it seems to be under much more active development than Subsonic. I'm currently running Subsonic and Airsonic in parallel.
Once they get a Debian build, I might jump ship, as it does not seem like much has happened with Subsonic since it went closed source.