Error message with WP Smush

Two questions. First off, we receive the error "No file content sent." for quite a few images that are trying to be smushed on our website What does that mean and how do we fix it? It looks like it hasn't been smushing images for a little while now.

Second, for some reason our live website is not showing up in our list of websites, only our staging server. How do we update that?