Plex is very picky with TV shows.
Make sure TV shows are in a TV show library. No mixing movies and TV shows in the same library.
Make sure you are using Plex recommended file naming and structure. See Your Media, specifically, TV Show Files (Naming and Organizing).
Plex matches against the tvdb.com, so use their structure for season and episode numbers.
If you restructure/rename shows, you may need to Plex Dance the entire show. This clears old metadata out of the Plex database.
For example:
A TV Library <--- TV Library points here
/Pushing Daisies
/Season 01 <--- two digits for season
/Pushing Daisies - s01e01.mkv <--- spaces & dashes important.
/Pushing Daisies - s01e02 - Dummy.mkv <--- Plex ignores everything after episode number. Can add episode name if you wish.
If the files still do not appear in Plex, analyze one of the problematic files using MediaInfo, save the text output, and attach it to the thread.
