Name your episodes according to TVDB DVD Order.
Edit The Show
Advanced Tab
Select DVD Order
Since this show has already been matched - I assume - you may need to do a little Dancing with the DVD Order Edit at some point in the process and I’ll also assume it’s at the Fix Match part (I can’t recall exactly where I employed it… it’s been a while)
The Plex Dance®:
- remove show from library - all of it
- 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 as well as name them in TVDB DVD Fashion
- replace corrected show into library
- update library
All Steps. In Order. No Shortcuts.