Theme Dev, Custom Header, Default Image

Either I’ve found a gaping bug in WordPress or I’m doing something wrong (presumably the latter). I’m developing a theme and experimenting with various customization options. I’m having trouble getting the default_image to behave as I expect it to for custom headers.

Here are the steps I take:
1. (in my theme code) I include add_theme_support('custom_header', $args) and in my $args there is a default_image specified.
2. (in the dashboard) I activate the theme and there’s my default image. So far so good.
3. I customize and say to Hide Image, click Save and Publish. Now the image is gone. Excellent.
4. I customize again and this time I click Suggested Image. I click Save and Publish and there – in my preview – is the default image back again.
5. I close the customization and look at the site. Or, I open the customization again. Either way, the default graphic is not saved.

I figured I would find a theme that does it right to find out what I was doing wrong. So I used the Feature Filter to find only themes that had a custom header, and selected several which appeared to have a masthead graphic.

Every theme I tried had a default image set. And every theme I tried behaved exactly as mine did. Once the default image is removed, it never comes back. The themes I tried were Violinesth Forever, Indore, and Irrigation.

As an added bonus, Indore seems to have given my theme an ugly icon which will not go away even after I delete the (Indore) theme. At first I thought it was an IE bug, but the same thing happened in Chrome.

Anyone have any ideas? Thanks in advance.