Apple Watch Playlist Not Able to select “Play”

1. I have the same grayed out playlists and play buttons, but I can play the songs from my watch on synced playlists (without music or match subscriptions by doing the following from the watch: Music > Library > Downloaded > Playlists > [Select Playlist] > scroll/swipe down > select any song. That song will play, as will all the other synced songs on that playlist. It’s a colossal pain, but it (currently) works.
2. For years, I could just play these playlists from Apple Watches by tapping them (without subscribing to iTunes Match or Apple Music). Since roughly watchOS 10, I’ve the same problem you’re having. If I’d known something as simple as music syncing required ongoing payments, then I’d have bought a Garmin Watch. If this stuff like music syncing remains paywalled, I will be very tempted to change to another ecosystem for my next phone, watch, etc.

Is this the case with all the playlists? Or just this one? What troubleshooting steps have you taken? The basics for an Apple Watch are to turn it off and turn it back on again, and if that doesn't help, unpair and re-pair it.

Glad you figured it out!