Sometimes you might not find certain movies and shows on various lists in Gaia. This is most likely due to you having enabled Kodi filtering. This problem has nothing to do with Gaia.
Kodi has a feature to hide all the movies and shows you have already watched. To disable the filtering, open Kodi's left-hand sliding menu (press the left key on a keyboard). In the menu there is an option that can toggle between "All video", "Unwatched", and "Watched". Set the option to "All videos".
Last Updated: 18 Jan 2018