Thanks for getting back to me, Kenneth.
Perhaps there's something I'm not getting, but I don't see how that will help. As the plugin author says, the problem is with Graphene's treatment of the image source. Did you check out the link? Here's the relevant part:
I downloaded the Graphene theme and played around with it myself. The graphne_get_attachment_id_from_src() function doesn't seem to work, it just returns null.
RWP has an internal, similar function but that doesn't work either.
I don't really know any good solution to this actually. The problem in this case is rather the way the theme is made than how RWP is working.
However, by hard coding the ID of the selected header image I got it working perfectly. It's just the hard coding stuff we don't want...
So I'm not sure that creating a new template would actually solve anything? Besides, the plugin author is just helping me figure out how to get the code working, he's not writing any templates or files for me or anything, so I'm not quite sure what you mean by that?
I've been trying to figure out what it means to hard code something because that seems to be the key to me understanding this issue. All I can really come up with at this stage is that hard coding simply means using something precise rather than a code, so in this case, I believe that would mean putting the header img url directly in the file. If I'm right about that, then wouldn't creating a child theme with a modified header.php file still involve hard coding the img source?
Sorry about my confusion! I appreciate your help :)
(BTW, I already have a child theme, I just haven't finished transferring the theme options/settings, nor have I had a real reason to use it, so it's kind of just sitting there, inactive...)