Thanks for asking and sorry for the issues you are facing.
Are you using Slider Revolution on this page as I have seen users facing the similar problem and Slider Revolution was active over there, please make sure that the slider you have assigned actually exists. Along with that, please make sure that you are update to date (X 6.2.5 and Cornerstone 3.2.5).
You can review our theme and plugin update guide.
If you still have problems kindly get back to us with the result of the steps above and URL/User/Pass of your WordPress dashboard using the Secure Note functionality of the post to follow up the case.