Hello There,
I can see that you have updated X to version 6.1.6. You must also update Cornerstone to version 3.1.6. At the moment you are using an older version. 3.0.4 will not work and not compatible with the latest version of the X theme. Could you please update to the latest versions?
- Cornerstone 3.1.6
This latest release contains fixes for several issues so be sure to check out the changelog (http://theme.co/changelog/).
_After doing the updates, always remember to clear all caches (if you are using WP Rocket, WP SuperCache or W3 Total Cache) when updating so that the code from the latest release is always in use. This will help you to avoid any potential errors.-
Please let us know how it goes.