Yep, that’s how i did it in the end, although i changed the path of the default image in functions.php to the path of my own header in the images folder. For some reason it ignores the featured image for that page, so you have to set the default image as the one you want to appear on the blog.
I have the same problem as this, I’m pretty sure the problem is occurring where the code checks if the page is singular, obviously the blog isn’t and so it is referring to the default image.
I dont have a solution yet but will post when i work it out
