TV program with metadata ONLY in the first season

Plex is very picky with TV shows. Make sure you follow the naming standards. See Your Media for details.

If you change the file names/organization, then Plex Dance the entire show. FYI, when you add the series back to your library, it may be easier to add just a few episodes from each season. If Plex recognizes them correctly, you can then move the remainder back to the library.

Plex is working on a new TV show scanner. It is still in beta, but available starting with the 1.22 releases. It may provide you better matching results. If you try the new scanner, you may want to create a new library instead of converting an existing library. That way if the new scanner does not work you still have the original library available.