Playback not working with Mac Music app

Yesterday, the Music app on my Mac Mini suddenly stopped working. The app opens fine and all of the playlists and songs appear okay, and I can navigate among the playlists without any problem. But when I click on a song nothing happens. The Controls > Play menu command also does not respond.

I have already tried the following, but none of them worked: quitting and restarting the Music app (multiple times); restarting my Mac; updating to the latest OS version (Sonoma 14.4); clearing the cache in com.apple.Music and restarting the Music app; logging the app out of my Apple account; logging back in; and everything else I can think of.

I use the app only to listen to mp3 files in my local library, and I do not sync files with the cloud. The mp3 files are still on my local disk (I can access them by control-clicking on a song title and choosing "Show in Finder"), and the song titles are not grayed out in the playlists. I do not subscribe to Apple Music, and I have only a handful of music files that I have purchased over the years from iTunes/Apple Music.

Any advice or suggestions would be most welcome.