Linux Distro: Linux Mint 22.1 Cinnamon 6.4.8

I was also running into this today. Have to set album art twice for every album, since the first never applies correctly.
I'm editing audio files with no metadata so I've been adding song name, artist, and album info before searching for and applying the album art, then saving.

Sometimes it appears to have stuck, and then I'll see the song again later and the album art has reverted back to what it was before I changed it, which seems to be an image randomly chosen from the album art directory.