Another user here, with the same problem. It is frustratingly annoying. When you inspect element the element is there for the header but the image will not be displayed no matter what size. It is only displayed in the editor. I have not gotten it to work live. I have tested what you just suggested and it did not help.
I think I have the same problem. I have two websites (both running WP 5.4 and Flat Responsive Pro 4.5.0). Both have a Smart Slider Widget in the Banner Wide Widget Area.
On both sites the banner/slider is visible on the home page. On one of the websites the banner/slider is also visible on all other pages. But on the other website the banner/slider is not visible on the other pages.
I have checked al settings, but can’t find any difference.
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