Attempting to edit CSS

I'm having an issue when trying to edit CSS for a page. I get this text (attached). Its only happening on our production site (using Chrome/Firefox). Has anyone ever seen this before? I've tried incognito/private browsing in case my extensions were causing havoc but no change. There are no extra plugins between our testing server and our production (we used duplicator for the transition). It seems to be happening only with the CSS editor (the template editor works fine). Thanks for the assistance!