Header images stopped displaying.

All the header images stopped displaying. Nothing was changed, and now nothing is displaying. When I try to edit to header, the image is still there. Images follow the image guidelines and were displaying fine for months.

I've been reading forums and help guides and cannot find an solution to our problem. Any assistance would be appreciated.

When you say header images do you mean ones that are in the background as a banner? Ive had this happen so and unless you choose an effect, theyre not showing.

Yes I mean the image in the background as a banner. I did not choose an effect. They were added months ago, and were displaying correctly. And then one day, they stopped displaying. Nothing was changed. I've read all the guides and can't find what to do. So frustrating,

Just found more forum posts on this: 

For now, I am using effects with film grain, setting at 0, to make the images visible. I will look into any CSS code used.