Plex Documentation → Your Media → Naming & Organizing Your TV Shows
Make sure you follow Plex naming and organization requirements.
Plex Dance the show after naming/reorganizing.
Example:
/TV Shows <-- folder added to tv show library
/Game of Thrones (2011) <-- show_name (intro_year)
/Season 01 <-- "Season" in English
/Game of Thrones (2011) s01e01.ext <-- sXXeYY format required.
/Downton Abbey (2010)
/Season 01
/Downton Abbey (2010) s01e01.ext <-- ext = mkv/mp4/etc.