Sound data not supported - but there's no sound included.

Hi guys

I've created three test videos in Express...

The attached file is shot from the screen and is in danish - but translated it says:
"The sound data is not supported"
BUT none of the videos include audio...

(The video runs perfectly, but the error message pops up every time....

All other ordinary mp4 videos we've got on our server works without problems.
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Mac - Ventura 13,5