[Theme Horse Support Team]

HI Sorry for the late reply. We are also searching about it. After searching a bit of it we found that some code. Please add this code inside theme folder -> functions.php anywhere you want.

// fix ssl handling for header_image theme_mod
function fix_theme_mod_header_image_ssl($url) {
if ( is_ssl() )
$url = str_replace( 'http://', 'https://', $url );
else
$url = str_replace( 'https://', 'http://', $url );
return $url;
}
add_filter('theme_mod_header_image', 'fix_theme_mod_header_image_ssl', 10, 1);

If you got still problem then feel free we will try our best to solve your issue.
Thank you!