Bug: Error while editing existing topics, posts and replies in the front-end

Hey everybody,
i noticed another small error while editing existing topics, posts and replies in the front-end. When I want to apply the changes, a small black bar appears at the bottom behind the editor window with a red line. The page is not reloaded or the changes are visible. If I update the page manually with F5, then the changes are taken over. For me it looks like this, so the changes would be saved, but it is not displayed correctly in the frontend.
Is the error already known?

Thanks!

Greetings
Sebastian