Certain downloaded albums won't transfer to my iPhone

I've been listening to all of my music on CDs for several years and typically upload a CD to my computer, then sync the CD to my iPhone. I just upgraded to a new 13-inch MacBook Air from my 2017 computer (same model). The two computers transferred beautifully and all of my downloaded music is now on my new computer, but when I tried to put my music onto my iPhone, all of the album covers switched around so that albums had completely different covers. Someone said to delete apple Music and re-sync my iTunes library, so I did. This worked, except for the fact that some of the albums that hadn't previously been on my phone wouldn't transfer. Some of them are new and have only ever been on my computer; others had to be deleted from my old phone because there wasn't enough space, but now that I have the space, I want to put them back on.

I've tried selecting "Entire Music Library" when I sync, I have disconnected and reconnected and restarted and checked and unchecked boxes and clicked and dragged, I've turned my location on and off, I've checked to see if I have enough storage (there's plenty), I've backed up, I've deleted and re-downloaded, and nothing has worked. The closest I was able to come was adding all of the problematic albums to a playlist and transferring that playlist to my phone. It showed up and listed all of the albums, but they are greyed out and when I try to play them, a message comes up that says they aren't available in my country or region, which is ridiculous because a) I live in America and these are almost all American artists; b) I had no problem getting the music onto my computer, and I've even had some of these exact albums from these exact CDs on my phone not long ago, and c) I OWN THE CD. IT'S MINE. I BOUGHT IT. AND I BOUGHT IT IN THIS COUNTRY OR REGION. So I absolutely refuse to accept that I simply can't have my own music. If anyone has any recommendations, I'm all ears. I just want to be able to listen to the music that I own. Thank you.

[Re-Titled by Moderator]