Only 187 of 800 movies showing up

I’ve got an 1 TB HD attached to the ATV. Works great. I wanted to use Sapphire (now using “Files” - I already have all the cover arts and they all show). When importing the data in Sapphire, only part of my movies are seen (even if they are located on the first level of the directory). And some collections (movies in specific sub-folders) are empty and some collections the files are there. They are all mp4 files. Any clue why some shows and some not? :?: