Hi @keckel,
I’ve had a look into the diagnostic that was on your account and can see you’re hitting the memory limit on your speakers.
Sonos needs to index the tracks for your music library and they’ll be stored on the speakers. While there is a 65,000 track limit, there is also a 3.6 MB Store Size Limit as well as tracks potentially taking up more space due to more metadata. Due to hitting the track and memory limit, this will be what is preventing you from making changes and updating.
I understand you’ve cleaned up a few tracks from your music library, but it’s likely you’re still hitting this limit. The speakers you have in your system are quite old, with the Play:3 being over 10 years old. Due to the age of the speakers, they have less memory to work with than newer devices.
In this case, I’d recommend using Plex since you’ve reached the track and memory limit with Sonos, as it works separately from the 65,000 tracks you have on Sonos.
I hope this information helps!