Baffled by Music behavior

[Elgibby1]

I subscribe to Apple Music, my library is synced among several other devices. My iTunes library and the music files are on my iMac. 

 

I recently noticed that a ton of files -- more than 1,000 tracks -- were no longer living on my computer but had been matched/uploaded to the cloud library. It took days to get it all back where it belonged; some tracks that had been uploaded came down in the same format. Those that had been matched came back as Matched AACs NO MATTER what they had been matched with -- so my Apple Lossless files came back as Matched AACs. Luckily the vast majority were re-rippable or downloadable from original sources.

 

My question is: why is this happening? It doesn't seem to matter the source of the original files. It happened to ripped CDs, to downloaded mp3s, etc. 

 

But it doesn't happen to everything. (Except that when I first noticed that pile of 1,000 +/- tracks, the vast majority were from 2018! I thought OK, we moved that year, the computer was disconnected for a while, maybe ... ? 

 

So I've been keeping an eye and it's still happening randomly. This morning (see attached image), I downloaded the tracks to an album I bought on vinyl. A couple of hours later, now there's two of everything: one with Cloud Status Waiting, one with a download icon and Matched, both with the same date and time added. This is driving me crazy, which is becoming a mighty short trip. In this particular case, I had deleted from my library a very old low-res version of this album before I added the new. (EDIT: Just looked again, it also happened to two more downloaded titles and one ripped CD. The tracks from the CD are listed as matched MPEG-4. The original Apple Lossless are WAITING under Cloud Status.)

 

If I delete one set of these tracks, I'll have to re-add the other. Makes no sense. 

 

What is happening here?