Ah, I was talking about windows 10 UWP which is only available in kodi18 beta. Not sure what the issue could be between standard windows version and android version.
Possible a codec that android cant play, so isn't visible?
On Android, are you viewing google drive via the "Videos" section in kodi?
if so can you try viewing google drive via "File browser" in kodi (Not video/files mode), to see if it can see the files present?
If you can see them in the kodi file browser you can force kodi to pick them up as videos using advancedsettings.xml file.
You can "Add" file types that kodi will associate as a video file
https://kodi.wiki/view/Advancedsettings.xml
Section 2.3.1 = add/remove video extensions
You could also try and identify which videos aren't being seen and try to see if there is anything different about those files (extension/file size etc) that may help pinpoint the issue.
Also, running the kodi 18 pre-release on android, it may just be a bug.
Other than that, not sure what else could be the cause.