This all started with trying to clean up my album artwork, as well as my music library in general - but the album in question has been deleted via iTunes & verified to be gone via iOS Finder...and doesn't show up in a search of the iMac HDD or the NAS where the Sonos controller is pointed.
Any suggestions or exposure of my ignorance is greatly appreciated...
Best answer by Airgetlam
It only seems logical that there's still a version of that album existing on your iMac, but not where you're looking. Since Sonos doesn't "store" any music itself, it just works from where you point it to to play, that's pretty much the only solution.
Since you removed the streaming possibility (damn you!), then I'd be taking a look at where the Sonos is pulling from (looking at the Sonos controller to see exactly where the library is pointed to). I know at one point when I updated iTunes, it changed it's location for data storage, and I ended up with two slighly dissimilar and yet similar libraries, until I turned on that feature in iTunes to consolidate everything, which ended up putting all of the things in one place. I think that was a few year ago (iTunes 3 to 4? Not really sure), but I ended up with a couple of different "music" folders nested in my iTunes folder.
I'd be poking around, and searching for the file names. Sonos can't play what you don't have somewhere...unless the laws of time and space have been broken