With all these changes you probably need to do the plex dance: @JuiceWSA said:
The Plex Dance®:
- remove show/movie from library
- rescan library files
- empty trash
- clean bundles
https://support.plex.tv/hc/en-us/articles/200392106-Library-Actions <— scan library files, empty trash, clean bundles- bring names and structures into compliance/Move LMA/etc
- replace corrected show/movie into library
- rescan library files
All Steps. In Order. No Shortcuts.
This should clear out any metadata and settings interfering with your changes. Simply changing a file name will seldom correct a PLEX matching problem