What do you mean by “episodes are not read”?
Are they not scanned/catalogued to begin with or are they listed but not getting any metadata?
Not sure what platform you’re using and if there could be a permission issue?!
The names as such seem ok (though, personally I would just have dropped the : instead of replacing it with a -… but that should apply to all files, not just the 16 episodes).
Not sure if it applies here, but if these are downloaded rather than personal rips, there could be some embedded metadata overriding plex’s ability to sort them. Might need to strip out or edit the information using an editor of some kind, like mkvtoolnix gui.
Might not be your problem but could be worth checking.