Your problem is you’re using MP4/M4V files and have Local Media Assets at the top of the lists in your Shows Tabs. Move it to the bottom. Then Refresh or…:
The Plex Dance®:
- remove show/movie from library
- update library
- empty trash
- clean bundles
https://support.plex.tv/hc/en-us/articles/200392106-Library-Actions <— update library, empty trash, clean bundles - bring names and structures into compliance/ or the ultimate bundle reboot operation
- replace corrected show/movie into library
- update library
All Steps. In Order. No Shortcuts.
Also make sure your files are properly named - FileBot (link in my signature) is probably the #1 Plex Companion.
If you use MP4/M4V files you should move Local Media Assets to the bottom of every Agent list everywhere - under all tabs or this very same thing will continue to create problems.

