Oh, I can think of something…:
Plex is looking inside those mp4 files for their embedded title field and not even seeing your file names - which are broken, BTW… everything in [Brackets] is ignored by Plex - the YEAR field goes in (These).
After you fix all your file names…
Demote LMA to the bottom of the Active Agent List under every tab in shows and movies…
Report what happens in a few days… I don’t know exactly what is going on, but it’s not odd that the only files that escape the collection are mp4 files. Not odd at all. Considering Plex’s DEFAULT location for LMA is right at the top of the list - so every person on Earth using MP4/M4V files will basically be UNABLE to use Plex as it’s designed… and in 20 years not ONE of us has been able to get that message through to Plex.
Hot Tips for those with file naming issues - like you:
https://support.plex.tv/articles/naming-and-organizing-your-tv-show-files/
https://support.plex.tv/articles/naming-and-organizing-your-movie-media-files/
Not sure how many files you need to fix, but this:
can make short work of it…
I recently used Filebot to put over 4000 movies in unique folders, turning a year long job into a week. Of those two time spans - I prefer the latter.