Images get deleted when updated

My background image also disappeared when I updated the theme. I have re-chosen the same background image and other background images, experimenting with various types of tiling to be sure the image is not simply hidden, but even though you can see the background image in the dashboard, no background image displays on the actual site. The background image was fine before the update.

I thought maybe the solid backgrounds (black) I had chosen were somehow interfering with the background image, so I cleared all the solid-color backgrounds and left only the background image, but still there is just a black background being displayed but no background image.