I have two music folders in my library where my iTunes is running from (one for the actual MP3 files location and the other for the location of the iTunes info like Playlists). Everything works great, except when I added a new playlist to iTunes and added a few songs to it.
When the 1AM Automatic Update took place, my computer showed no error messages (in the Sonos controller, nor in the Windows 10 Event Viewer) and all the playlists were removed from Sonos (they still existed in iTunes, and all the MUSIC was still there playable by Artist, etc). When I *manually* initiated an update of the library, it worked.
The next night I added a few songs to the playlist, and the same thing happened, so I tried an experiment. After the library was updated manually, I added a few songs again, and set the automatic update to take place in 5 minutes. When the start time came, the library started its update and I left the controller open on my PC. After a length of time I got a popup, and a message in the Sonos Error Log that said "An unexpected error occurred while importing playlists." When I then *manually* initiated the update, the library updated properly.
So it looks like Automatic is failing, but Manual is working :(
The only thing I can think of is that when I do the manual update, Windows prompts me with the User Account Control popup that asks if I want to allow this application to make changes to my system. I always say YES, but I'm wondering of something in the Automatic process is "asking that question" but not getting the correct answer, or the security is set wrong on the app itself.