My system is using the Plex TV Series scanner and agent. See screenshot below.
The Plex TV Series scanner uses The Movie Database and TheTVDB information on episode ordering.
Please show how you have your files named and organized, including file extension.
Plex is very picky with TV shows. Follow Plex requirements as outlined in the documentation linked in my prior reply.
Plex Dance the entire show after any renaming/reorganization.
