I just found out it's not the code (html or css).
I manually replace the image reference in the css file
- to an alternate image
and it works.
So it has to be the image.
Can you place this image into the background of a section (cover not fixed centered).
Change opacity to 65%... add junk text in white into the div.
Preview it... it should be work fine.
Export it... image will not be visible but highlighting all text on the page will show the text.
Can you verify this. If so... it has to be the image. Otherwise... I'm missed something.