Plex is naming some of my files “Up” (as in the Pixar movie). It even uses the “UP” background art and tags, etc when I click on it. PerPLEXed!
No, Plex isn’t naming them that, it might be matching them to that name though. The files are likely the same name they were when you put them in the library. And the naming convention you use probably what is confusing the matching agent you have selected for that library.
Refer to this support document for naming conventions that work well with Plex: https://support.plex.tv/hc/en-us/articles/200381023-Naming-Movie-files
If you have things in the name like DivX, or other info about sources, etc. This is likely what’s causing your problems… You can use an app like FileBot to batch rename files. It works pretty well… 
