Was the OS on your Mac updated? Do you have auto updates enabled?

No, the OS hasn’t updated (still Sequoia 15.6) and I haven’t updated to the newly-offered 15.6.1 for the reason that there is always an issue after updates.

Hi ​@Philip Cole 

Thanks for your post!

I am sorry to hear of this issue you are having with music going missing from your Music Library. 

My assumption would be that this has something to do with the files themselves, but it’s difficult to say.

I recommend you get in touch with our technical support team who have tools at their disposal that will allow them to give you advice specific to your Sonos system and what it reports.

I hope this helps.

Thanks Corry.  In fact, in a moment of desperation as I felt I had nothing more to lose, I updated my IOS from Sequoia 15.6 to 15.6.1 (something which is usually guaranteed to muck up all my files) but on this occasion it seems to have put everything back in place.  So thank you for your advice but things seem to be OK.  Let’s hope they stay that way!

My thought is that there is something different with respect to the file format, names, or location for the problem files. Are there any special characters in the file names? I can’t explain why the phantom struck suddenly.

At a guess I would say its the infamous “local network” permission, which has a life of its own. Updates often secretly disable it, but here it appears it might have secretly enabled it, which was a win for the OP.

So much for my delight when Sonos was able to see all my music again. This did not last long and I have even less music which I can play. Sonos cannot now see ANY of my music stored in my iTunes files and, when I try to update my Music Library, all it now sees are a few random albums which I purchased via Amazon and which are stored under Music/AmazonMP3.  

All my music was, and still is, filed under /Users/philip/Music but for some reason Sonos cannot see it.  Can you offer any advice before I take a sledgehammer to my whole Sonos system and replace it with some Apple speakers?  Thanks!

Hi ​@Philip Cole 

My advice is still that you get in touch with our technical support team who have tools at their disposal that will allow them to give you advice specific to your Sonos system and what it reports. More importantly, they will be able to start a remote desktop session to your computer and figure things out for you that way.

It sounds like the issue may be due to folder/share permissions.

Thanks.  I’m in touch with them now.