It looks like the problem is some of your images are redirected. When I inspect one of the missing images in Chrome, right-click on the background-image CSS and open it in a new tab, it is redirecting to the homepage. HTTP Header Check returns a 302 found, so somewhere these images are still set to redirect. Perhaps you have a caching plugin or a redirect plugin? I’d try deactivating all plugins and then turning them on one by one to identify what may be redirecting. You could also check .htaccess.
