I have been trying to save a roughly 30 minute movie that I edited with no success. When I save the movie, everything works as it should, but when I go to the saved file there is no thumbnail and the movie cannot be opened with any media player. Oddly enough, the saved file is an MP4 file and the size seems about right (about 4GB for a 30 minuted 1080p movie), but no media player can open the file. In addition, when I open the file in Movie Maker, all I get is 7 seconds of a black screen with no audio. What is even crazier is that I just used Movie Maker to edit/save 3 movies a couple of days ago, the only difference being that these videos were much shorter.

This is what I have tried so far:

Opened the Movie Maker file and attempted to save the movie again

Created a new Movie Maker file and reedited everything and saved the movie

Converted the imported files from MP4 to AVI and saved the movie