Hi @Rollinsford 

Welcome to the Sonos Community!

Please try removing Spotify from Sonos completely:

iOS or Android

1. From the Settings tab, tap Services & Voice.
2. Tap the service you wish to remove from Sonos and tap Remove Account. If you’ve added multiple accounts, make sure the correct one is selected before removing.
3. Tap Remove.

macOS or Windows

1. From the toolbar in the top left corner, click Manage > Service Settings.
2. Click the service you wish to remove and click the - (minus) button if you are using macOS or Remove if you are using Windows. If you’ve added multiple accounts, make sure the correct one is selected before removing.
3. Click Remove.

If you have the Spotify app installed, please ensure it is logged into the Spotify account you want added to Sonos. Then, add Spotify to Sonos once more.

If that didn’t help, please unplug all Sonos devices from power, turn off your router for at least 30 seconds, then turn it back on. Once WiFi is fully up-and-running, please then turn on the Sonos devices again.

Finally, 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. Please test the system for about 20 minutes after the reboot before calling in.

I hope this helps.

It could be caused by different reasons like below. You can check your  spotify app. I will share some reason I have met before.
1.The original songs or playlists were deleted by the artist or creator.
2.wrong Internet connection or wrong wifi setting.
3.subscription plans expired.
4.VPN network settings (the previously downloaded songs could become unavailable on Spotify if you changed the region of your VPN network. That's because Spotify is not allowed in certain countries and regions.)
5.Exceeded limit of 10,000 Songs
To prevent Spotify songs from disappearing again, you can have the Spotify songs downloaded to common formats such as MP3, it will become easy to stream Spotify to Sonos speakers without trouble. I have subscribed Spotify for two years, but one day I forgot my premium account so I can not access my playlist. So annoying! I am trying to convert Spotify files to MP3 now, it worked! With converting tool, I can get full ownership of the downloads of Spotify songs and keep them on my Sonos. I have tried different converters before, but I recommend AMusicSoft, there are no guarantees for you that this method will work, but it's worth a try. Or you need to contact service team to check your Sonos device.

I hope this guide can help you: “How to Add and Play Spotify on Sonos” https://www.amusicsoft.com/spotify-music-converter/play-spotify-on-sonos.html

More information about how to play Spotify on Sonos will be tackled in the post alongside answers to FAQs. You can try converting the tracks using tools like AMusicSoft (https://www.amusicsoft.com/spotify-music-converter/) (if ever you are a free Spotify user).