Apple Music: Server identity error with local files

In Apple Music I am seeing the error "Unable to verify the identity of the server “rtmp2.abnvideos.com” when trying to play certain music files.

• These are Local files I ripped from CDs or even tapes that I own from many years ago (some are local band demos).
• They appear in the "Songs" list with a dashed "cloud" icon OR a cloud with a 'slash' through it, which might indicate they might be stored in my cloud library.
  • Double-clicking the song pops up the error, and clicking "OK" brings up a dialog "Getting playlist" which cannot be dismissed... I have to force quit Music to kill it.
• However, if I select "Show in Finder," the files appear and will play directly from the Finder... so it's the intersection between the files and Apple Music that seems at fault.

Other Notes:

1. I have upgraded my Mac several times over the years, so maybe there's a certificate issue there? The "Computer name" (i.e. Home folder name) has changed over the years during upgrades, since I often do NOT get rid of the old computer every time I get a new one.
2. I DID have a subscription to Apple Music (once or twice), but these are my own local files, so I don't think that would be an issue.
3. If I try to use File > Library > Update the Cloud Library, the indicator "Loading cloud library" appears (bottom left of the app) and stays there for a VERY long time (I've never had the patience to wait for it to finish)!

While I do have over 7,800 songs (which are NOT Apple Music files), in my library... I cannot figure out why these songs are a) on my computer, but b) not accessible to the Music app.

I am wondering if this is a certificate issue based on changing the Home Folder names over XX years and YY different computers? Any advise or ideas to get my ducks back in order would be appreciated!