Local music library disappeared

After restarting my Mac (not for an update, just a normal restart), I opened the Music app and suddenly it's completely empty, all my local songs and playlists gone. I double-checked the media folder and verified all the music files were still there (they were). I then checked the overall Music folder and noticed the .musiclibrary file was much smaller (had gone from 79 MB to 28 MB), as if the library had deleted itself. I went into my Time Machine drive and grabbed a previous version of the musiclibrary file and replaced the current one with the previous backup, but Music just seems to refuse to acknowledge that musiclibrary file. No matter what it always opens up empty. I have tried restarting the computer and no change.

For reference, I do not have an Apple Music subscription and I do not have iTunes Match. The 'Sync Library' option is off and I have always had it turned off. I just have a local library of music files and that's all I use.

Thanks anyone for any suggestions you can offer,

Stuart