Thanks for asking.
As you have rolled back the changes it's difficult for us to see troubleshoot the problem. If possible please setup a staging site and in that update the site to latest version using the steps mentioned in theme and plugin update guide. In case you encounter the same problem, please let us know so we can take a closer look.
In ticket it's mentioned that you updated only Cornerstone. Please make sure to update X and Cornerstone to latest version other wise it will create compatibility issues.