Plex has no support for multiple artists.
Equally important to metadata is the hierarchical storage into subfolders. Where is it located?
What kind of meta tags is used in the file? It should be ID3v2.
Remove APE and other obsolete ones.
Forget the Windows file properties. They don’t convey the whole picture. You can use e.g. Mp3tag - the universal Tag Editor (ID3v2, MP4, OGG, FLAC, ...) to see all tags and also clean up the obsolete tag stuff etc
