Since the update for spatial audio was released the not encoded error is happening most of the time. This only happens when using Apple Music via the Sonos app and is not just limited to the Era 300s.
Tracks that have been uploaded using the iTunes Match service display the error but other songs won’t play either despite everything being fine before.
I can get around this playing via Airplay or deleting the tracks from my library and adding them again from Apple Music. This isn’t an ideal fix though as I have lots of music that isn’t available on Apple Music. I also have 100s of playlists and I can’t do this to every one.
I’ve tried all the troubleshooting tips that I’ve read and nothing has worked.
This is obviously an error caused by the new spatial audio music update; Apple and Sonos need to get together to fix this because it’s ruining the Sonos experience.
Best answer by Corry PView original