Apple Remote "forgets" tracks in a huge local Apple Music Library

I have a 1.5TB music library on an external drive on my M1 Max Mac Studio, and sometimes tracks are dropped/not visible in the remote app via my iphone or iPad. If I go to my home office and log on to the Studio directly, I can see all the songs, tho some have gotten unchecked. I can "restore" the song by clicking it in the Apple Music view on my main monitor, it gets a check mark and is then viewable/playable in the Remote app.

Over time, the app seems to forget a lot of songs when I haven't played them in 6 months or so. Is there a way to lock the files so Remote doesn't forget them?