What type of shared library are you using? Is it a NAS box, or a PC/Mac share - if its the latter, are you using the Netbios name, or IP address etc?

It's a Mac but I don't know the answer to the next questions. I had it on the app for a couple of years- did the upgrade a few weeks ago and it disappeared.

You likely need to share the library folder using the SMB v2 (or higher) protocol and (ideally) give a user/account on the PC permission to access the folder as ‘read-only’. Then add the network UNC path to the mobile Sonos App with the user/credentials alongside that has the read-only access.

Here’s two Sonos Support links and a YouTube video aswell, that each will hopefully assist you to setup Sonos access to the share…

https://support.sonos.com/en-gb/article/share-your-macos-music-folder-with-sonos

https://support.sonos.com/en-gb/article/add-your-music-library-to-sonos

https://youtu.be/kjhKhDuvgDY

Thanks

I appreciate your help.

Stan