Since this issue really wasn’t making any sense it was clear that the TVDB API was not the root cause, I took a different approach:
- Removed the entire season of both shows from the NAS server entirely
- Empty Trash
- Optimize Database
- Clean Bundles
- Waited 2 days and repeated the 3 steps above (Empty, Optimize, Clean)
- Restart the NAS (which restarts Plex)
- Copy the seasons back to the server
Whatever the root cause of this issue was, the above somehow resolved itself. The best I can come up with is a caching issue that was cleared with the 2 days and restart. Pure speculation of course. Anyway, all my episodes are now there for both shows, including new episodes I’ve added since.
I do appreciate everyone’s help on this though.