Are the files valid video files at all? Do they play in e.g. VLC?
How are the file named? How are they organised in folders and subfolders?
Are you adding them into a ‘TV Show’-type library at all
or are you trying to mix them into your movie type library?
https://support.plex.tv/articles/201543057-why-is-some-of-my-content-not-found/
