Apple music cannot find the music file.

I have a 2021 Macbook pro running system Sonoma 14.6.1. I have 13,000 songs that I have rated and placed into 81 separate playlists over the past 25+ years. Suddenly, many of my tracks have an exclamation in front of the name. Double-clicking on the track opens a window that says,

If I say locate and look in the folder of the song's album, the track is not there. If I cancel the request, the song begins to play and the file is now in the album's folder. The song remains in all the proper playlists with its rating. I have rescued hundreds of songs by repeating this maneuver, but it will be thousands of songs and the problem has been recurring.

This database of music has survived many software updates, including the transition from iTunes.

Have you heard of this problem before?

Thanks,

Ben Trovato