Dear Ben,
There is no way to access data for an unsaved post, except maybe taking it via jQuery from the edit screen. That's how WP works. It's a common thing, you will find lots of developers stumbling into this issue/feature/whatever you call it.
Look in /types/embedded/frontend.php around line 85-ish. I asked our developers to first check for global $post before checking for ID, like this:
global $post; if($post) { $post_id = get_the_ID(); } else { $post_id = null; }
Once you are satisfied this is all you need from this thread, you can close it, but it will not be removed in any way. So you can save it, it will be here.
Regards,
Paweł