The weirdest thing seems to be happening, I am trying to add 3 videos to blender VSE, for this sake we'll call them 1.mp4 2.mp4 and 3.mp4.
Each of these videos is exactly 14 seconds long and within 150 kB of each other in size. They are all the same frame rate.
No matter what I do 1.mp4 is only about half of the video when I add it to the video-sequence editor, the rest work fine.
I've tried messing with the start and end frames and the frame rate but changing these doesn't appear to affect anything with 1.mp4's length.
I have also simply tried extending 1.mp4's length in blender but obviously there's no video on the second half.
I have played all 3 videos in VLC and they play just fine so I know it's not a corrupted file.