This happens on nearly every page of our site within the staging site. The pages are made of multiple advanced layout editor boxes, but clicking any one of the layout boxes shows all of the HTML in the visual editor, but in white-on-white. It’s also all in the text editor tab – but again, that’s for the whole page, not the individual box I should be able to edit. I’m including a private link to a screenshot of what I see on the page.