workarounds

Tags

You can of course let plex do all the work for you. But if you have your music tagged properly, you'd rather want plex to import your tags. You should instruct plex to do so under library settings: prefer local media. 

Genre

Plex differs from ID3tags in your tracks as it recognizes genre tags on the artist and the album level but not on the track level. However, the album genre is derived from the track genre if the tags are imported from your local media assets. 

If you want to assign the album to more than one genre, make sure that the id3tag genre uses the divider ";". Example: 

ID3tag: "Pop"           -> Plex shows "Pop"

ID3tag: " Pop/Rock" -> Plex shows one genre only: "Pop/Rock"

ID3tag: "Pop; Rock" -> Plex attributes two genres: "Pop" and "Rock"