I am having this problem and have tried all the tricks suggested here. When I rebooted everything, updates that I had made to playlists several days ago finally appeared but changes that I made this morning have not. Changes I make in sonos are not reflected back on spotify. There is clearly some bug impacting the speed with which syncing happens between spotify and sonos. I only have spotify so I can play it via sonos. If sonos and spotify can't get this to work reliably I'll ditch spotify and use a different streaming service that does work.
Same problem with a couple of other 'features'. Started yesterday as far as I'm aware.
1. Spotify playlists made in Spotify don't update to Sonos. 2. Sonos Playlists made through the Sonos Spotify interface don't appear in Spotify. 3. Searches on Spotify made through the Sonos app don't return results that appear when the same search is made directly on Spotify.
I've reauthorised the Sonos-Spotify link but the problem remains.
I just got this (below) from Sonos support. At least Sonos customer support actually responds to customer issues and provides updates, even when it's not their problem. Wish I could say the same about Spotify who just ignore everything.
Thank you for contacting Sonos Customer Care.
I am sorry about the issues you are experiencing with Spotify playlists and Sonos.
We have just received confirmation that Spotify is currently experiencing a system-wide issue with Sonos, specifically related to synchronizing playlists from/to Spotify clients and Sonos systems.
As soon as this issue is deemed to be resolved, I will reach out to you with an update.
I had the same problem this morning and the add-and-delete a playlist solution did work for me. I've also been getting intermittent "service unavailable" messages - I'm kind of tempted to try Beats instead, at this point...