Cannot access single page Divi Builder

Hello my name is David Train and I have several WordPress Sites. But at the moment I have a problem with one page that is completed and all content is on the page already. When I go on to the single page (in this case it is my home page) in the dashboard I cannot see any elements on the page to select. I have the divi theme installed. There is a not content whatsoever. The only thing I see is the yoast plugin options. So I cannot adjust anything within the page. in the divi builder page. But if I go on show website it displays everything. And also I can use the visual builder. This is really strange.

The blog I need help with is http://www.train-express-coaching.de.

The page I need help with: [log in to see the link]