My movies disappear from TV app library

Since upgrading to Catalina and now using the TV and Music Apps instead of iTunes my movies that I have copied from my BluRays and DVDs onto my Mac keep periodically disappearing from the library. The movies files are still in the Movies/TV/Media/Movies folder, but the only ones in the library are ones I have purchased from iTunes in the past. I can select the whole folder an import to the Library, but they disappear after a week or two. Very frustrating. The reason I do it this way is so I can watch the movies on our Apple TV 4Ks. If I can't get this to stop happening I'll have to move all my movies onto a Windows PC and use Plex and the Apple TV Infuse app to play them. (Already do for UHD discs since Apple TV won't play .mkv files)