Hi There,
Thanks for writing in! Upon checking your page, I see that you’re using an older version of X theme and Cornerstone plugin. You can see the latest version numbers from the following link (https://theme.co/apex/forum/t/troubleshooting-version-compatibility/195).
Please update your X theme by downloading the latest version from your Envato account (https://theme.co/apex/forum/t/setup-updating-your-themes-and-plugins/62).
Then to update Cornerstone plugin, you can delete the current version from your plugins section. Then head over to X -> Validation section and wait for few seconds to install the latest version automatically.
After updating, you need to purge your server cache, clear your browser cache and test your site.
Hope that helps.
Thanks!