All Movie Files Don’t Display in GUI?

1. home > movies – click on “movies”, movies are listed, but the count is 20% less than the number of movie files on the hard drive.

2. settings > media settings > library > videos – select drive that contains movie file, all movie files on the hard drive show up, total count matches hard drive count.

kodi clearly sees all of the movies, they can all be seen in settings, why don’t they all display in the gui?