I could not find any reason other than you have version 2.0.4 of Cornerstone which is not compatible with the version 5.2.5 of the Theme.
So please back up your website completely and update the theme to version 6.0.4 and the Cornerstone to version 3.0.4.
If you still experience the problem please read this article:
And if yet you have the problem kindly get back to us with the URL/User/Pass of your WordPress dashboard using the Secure Note functionality of the post to follow up the case.
Also, give us more information about the problem to be able to double check the case.