Hi There,
Thanks for writing in! Upon inspecting your site, I see that you have updated X theme recently but you’re still using an older version of Cornerstone plugin. You can see the latest version numbers from here (https://theme.co/apex/forum/t/troubleshooting-version-compatibility/195).
Please update your Cornerstone plugin by head over your Dashboard -> Updates section. In case if you don’t see any updates, you can delete your current version of your Cornerstone plugin and then head over to X -> Validation section and wait for few seconds to install the latest version automatically.
After updating, please make sure to purge your server cache as well as browser cache before testing your site.
Thanks!