Thank you for your reply. The problem is still there with the version you have linked.
After further investigation, I find that the footage from my camera, which I need to edit, does not display, but some other .MP4 files display as normal. The screen grab here shows the Mediainfo data for two MP4 files. The one on the left displays properly, the one on the right does not.
Also, I am disappointed that Videopad gives a 'Failed to load file' error message when I try to load .TS BDAV format video files from my Sony camera. I need to edit those too.