Homepage header image

Hello again,

I am experiencing another oddity on a few of my pages, but more alarming for my homepage. The custom image I select for my header does not display. It will however display on any page or blog post that I do not assign a featured image to.
Speaking of featured images, they also selectively work for pages, as they do not display for two of my other category pages that have featured images selected. Could you please assist me with this issue?