Hi @tjameslane.

Welcome to the Sonos community and thanks for reaching out to us and for doing the extra mile of starting with some basic troubleshooting steps. I understand that you wanted to share your music library with your Sonos ecosystem. I would like to share with you by going through these recommendations to help out.

I would recommend the following basic troubleshooting steps:

1. Reboot the router by unplugging it from power and plugging it back after 10-15 seconds to refresh network connectivity and delete temporary data stored on the router.
2. Reboot your Sonos devices.
3. Force close and re-open the Sonos app
4. Test if the issue persists.

I would also like to suggest the following guides to check if these things would also help fix the issue.

1. I had to change permissions for the folder where my music is stored.  It was set to “Custom,” and I changed it to “Read & Write.”
2. I then went to System Preferences > Security & Privacy > Privacy.  Under “Full Disc Access,” both the Sonos program AND SonosLibraryServer must be allowed.
3. Finally, the computer name and NetBIOS name must be exactly the same in both System Preferences > Sharing - and in System Preferences > Network > Advanced > WINS.

After that, update the Music Library.

Please let me know how it goes and keep me posted on the progress.

Thanks,