You might try a different editor. Here's a good free one:
Shotcut is a free, open source, cross-platform video editor for Windows, Mac and Linux
shotcut.org
I've seen paid stuff (including their free trials or limited-use-forever versions) do things that are clearly non-standard while continuing to call it standard.
A well-known DAW, for example, saves WAV files that nobody else can play because the file header is missing some critical information. But it can play its own files just fine because it knows what that information is. I wonder if it's trying to keep its non-technical-artist users locked in by making them think that everyone else is comically broken, can't even do something dirt-simple like playing a WAV file!
Anyway, see if free and open-source stuff works with other, unrelated free and open-source stuff. If it does, it's probably the proprietary thing that's wrong. The "unrelated" part means that both open-source apps must use the established standards correctly in order to work together.