Hi Panthercules, Thanks for your reply, and I am sorry you also are having this issue, not just me. WOW!, you have a huge collection…nice 
I have been using PLEX for nearly eight years, and I have always named TV Shows in the same way, ie. “TV show, in the TV Series folder, title of this folder, ie. ‘Star Trek - Discovery’ and then, S1, within this subfolder, all episodes for that season, ie, first episode is ‘S1 01 - The Vulcan Hello’.”
So this would look like:
TV Series/Star Trek - Discovery/S1/S1 01 - The Vulcan Hello’.
(This is the same way I have always names this)
All of a sudden, every TV show I try to add, comes up with “Major”, the Japanses Anime show?.
I also tried what ‘dokuro’ suggested in his reply, and named the show (above), as to how he suggested, with the same results, it came up as ‘Major’, so in my opinion, it is not the way we are naming these shows, I think PLEX have changed something in the background, with a recent update. I found, some Movies, also dont come up correctly.
It really is strange? Could this be, because the show I am adding, is 4K UHD? I dont know, just a thought?
Anyway, let me know if you come across anything that would help.