The definitve guide to tv show file naming in Plex: https://support.plex.tv/articles/naming-and-organizing-your-tv-show-files/
It also mentions why having part x at the end of a file name can lead to mixups.
Make sure to have either no embedded metadata in your mp4 files, or 100% correct ones.
If you don’t want to wrangle embedded metadata, make them less important for Plex:
Go to
- Settings - Server - Agents - Shows - TheTVDB
In there, grab the line ‘Local Media Assets’ with your mouse and drag it downwards, so it ends up being at the bottom of the stack of active agents.
Repeat the same under
- Settings - Server - Agents - Shows - TheMovieDatabase
- Settings - Server - Agents - Movies - Plex Movie
- Settings - Server - Agents - Movies - TheMovieDatabase
After experimenting with different file namings and encountering mis-matches in Plex, you may have to Plex Dance
