This link relates to a USB drive, but I believe the same works for a NAS Drive:

https://support.sonos.com/s/article/5031

Doesn’t the same thing happen if you use the Music app’s command File> Library > Export Library? With the care that where you put that file is the correct location in the “save” box, of course?

Hi,

Thank you for the tip, but I think this only works when iTunes existed. Now the app is Music, and there is no xml file. The metadata is stored in the file I stated in the original post, so it is mirrored onto the NAS. But  Sonos is not picking it up.

Hi, I tried this - exporting and storing on my NAS root music folder. I then updated library in Sonos, but it’s still not showing any playlists under ‘Imported Playlists’. 

Huh. I’m going to run into this issue shortly, as I’m swapping NAS drives to a Synology as well. Sounds like my assumption wasn’t accurate, though. 

Have you contacted Sonos support to ask them?

The iTunes .xml file is a text file - and so can be read in a text editor, like notepad etc. Maybe open the file and glance through it, to see the paths where the tracks are located - if they do not point to those stored on your NAS library, then you might need to edit the .xml file using a ‘find and replace’ to switch all the entries to point to the tracks stored on the NAS instead.

When done,  reindex the library in the Sonos App and see if that solves the matter.

I seem to recall the original iTunes .xml file was protected with ‘read-only’ permissions, so if that is still the case, then change the files permission in windows, or alternatively save the edited file (in memory) to a brand new file with the same name/extension, but in a different directory/folder and then replace the file with the edited one - at least that way, you will also have a backup of the original to revert back to aswell.

Hope that works for you.