My system the TVDB scanning plugin / media source seemed to just disappear, I don't know why!?
I fixed it 2 days ago by re-grabbing the plugin in "get more" information providers.
This has worked fine at the time, scanning in my library of TV shows again (movies, not impacted)
I just found 2 episodes of One Punch man, not updating, I don't know why?
The file permissions are correct, Kodi can even play them under the 'files' menu.
I've re-scanned the folder, it won't import them.
I even checked that TVDB does recognise the files exist.
What could it be ?