On my MacBook Pro, all of my songs in Music are listed but all of my playlists are empty.

I have a MacBook Pro running Monterey 12.5.1. I also have a 7th gen iPad, a 9th gen iPad and an iPhone SE. I periodically sync these three devices with my MacBook using a USB cable. A few days ago, I noticed that the Music app was missing from my iPhone, so I reinstalled it. When I tried to sync my songs, playlists, etc. from my Mac to my iPhone, all lists of playlist songs on my Mac as well as iPhone were gone. I still have all of the songs on my Mac and the playlist titles, but the playlists are empty. Now that I've synced with my iPhone, the same situation exists on my iPhone. The two iPads look fine. Needless to say, I am not doing any syncing with them until the problem gets solved.

I do Time Machine backups every hour. However, since my Music library is large, I moved it to an external drive a long time ago. So, I don't believe that I would find a current Music library backup in my Time Machine files. The external drive where my Music files is named Data 1. I back that drive up to another external drive, Data 2, twice a week. I also back Data 1 up to another external drive, Weekly Backups, once per week.

Thank you for your expert help. Based on your comments, I have two alternatives. One is to pay a $10/month fee to subscribe to Apple Music. I don't feel the need for this option. The other is to repopulate my playlists manually. Although that alternative is labor intensive, that is what I will be doing. I can't help but feel that a file that has playlist information has been lost.

I also realized that my relatively new MacBook Pro has a 1 terabyte internal drive, which should be able to handle the 2900 songs that I have in Music. So I will go back to keeping my Music files on the internal drive.

I'll investigate this option at some point. Thanks for all of your help.