Help with Spotify playlists

Maybe someone that is a little more technologically savvy can help me out. Playlist in question was originally imported from iTunes. It had 1200+ songs. When I am using my phone, all 1200 songs are available to listen to. However, when I try to play it through Sonos it is completely crossed out and won’t allow me to play.

So I logged onto the computer and here is where I kind of get lost. When I pull up the same playlist on the computer it only shows 400+ songs. I was able to copy those songs to a new playlist and Sonos now recognizes it. But I’m still missing a ton of the playlist. Why is there a disconnect between the computer playlist and my phone? It will be a bitch to manually add the rest of the playlist so it will be available via Sonos