I read this post here suggesting the use of Featured images to set custom headers for different posts/pages. It works great for a static front page, individual posts, and general pages using any of the 4 page templates from the dropdown. It does NOT work on a PAGE designated as the POSTS Page under the Static Pages customize option.
Note: I am using the sample child theme that was included with the parent theme but I also tested this within the parent theme and it not working there either.
I would really like to be able to designate a different header on the default Post page as well. I apparently can everywhere else. Any help would be appreciated.