Please check the issue is fixed, I reuploaded default files and enabled dev mode, the header appeared 

Guys, there was a small bug in the general html file of the master pages folder

Webster on line 10 

after this line: 

{if isset($imageControlValues.headerImage.src)}

insert this one: 

<div style="background: url({$imageControlValues.headerImage.src}) no-repeat; height: {$imageControlValues.headerImage.height}px;"></div>

then enable dev mode and refresh your website

Thank you :)

Hello folks, I am having a similar problem, I am running Oxwall 1.8.1, origin theme, but using a custom header image, nothing else has been changed except the menu item names.

My header image does not show, nor does it even show a place holder for the image. When i go to customize appearance, under Theme Customization, my header shows on block 3 for  custom header. The header has been used for several years but now no longer shows on the site.

So my steps to troubleshoot this was, 1. click reset next to the custom header, that in fact puts the default header back in place, and even shows on the site as the default header.

2. The default header is named header.jpg and resides in the images folder of the theme folder.

3. I changed the name of my header to header.jpg and replaced what is in the images folder of the theme folder, result was no header would show, not the default, not the custom header.

I cleared the cache, no joy, just no header image, even though it is the same name.

I am at a loss here.

Hi Ross,
Ok, you got me again ;) I owe another donation!

But, why would over writing the original file in the theme images directory not work? Or am I thinking to deep into this?

Appreciate your help!

Yes, overwriting won't work because this line is missing in both files.