This bug starts when the iubenda plugin (my GDPR plugin) is activated, this problem only exists in editor mode. The editor displays a blank page with all widgets present in the tree but not visible on the page. I had the same problem with the CSS Hero plugin. Example: I opened the header template, I can’t see the header but the footer was present, when I opened the footer the opposite happens. When I deactivate the plugin everything goes back to normal