iPhone 12 displaying incorrect album art

Hey - weird problem here, can't seem to find anything useful via Google.

Recently upgraded to an iPhone 12 Pro Max (running iOS 14.2.1) from an iPhone XS Max. When the new phone arrived, I did the phone-next-to-phone transfer of everything and it went fine. The album art for the music that was transferred over between the two phones looks fine on the new phone.

However, when I started adding new albums to my new phone via Itunes 12.11.10.26 on my Windows 10 PC, I noticed that while the album art for the newly-added albums is correct in Itunes, it's wrong on my phone no matter what I do. Changing the album art in the Itunes library and reuploading it to the phone doesn't fix it, and even changing it via Itunes on the phone itself only switches it to a different, incorrect album art of another album that's on my phone. The same issue is present with all of the albums I've tried uploading to the new phone.

I manually manage my music in Itunes, and running a sync (without changing that setting) didn't make any difference. Any suggestions?

Also, not sure if this is related, but figured it's worth mentioning: None of the music or playlists on my phone show up in Itunes aside from the few albums I've uploaded and had this issue with since I switched to the new phone. It shows that there's 40-something gigs of audio on the phone when you look at the device details in Itunes, but when you click on Music in On My Device in Itunes, it only shows the couple of albums I've uploaded since switching over, nothing else.