I’d first verify that the files in question are actually mp3 files. (and not just wav or aac or something else which just had their file name extensions changed)
If you are sure these are mp3 files, I’d check (and repair) them with software like this: MP3 Diags download | SourceForge.net
Then verify their embedded meta tags for accuracy and completeness. (using external apps)
Then perform the Plex Dance with the whole album.
