Forerunner 955 Spotify playlists show 0 tracks, won't sync

My Garmin Forerunner 955 used to work fine with Spotify, but sometime this year the feature broke. When I add a playlist to my library in Spotify then go to sync it with my watch it shows up with 0 tracks in it and obviously refuses to sync a playlist it believes is empty.

I've logged out of Spotify on my watch and phone, reinstalled Spotify on my watch and restarted everything but it has not helped.

Does anyone have any suggestions to get this working again?

Thanks