Sorry, but we can not find the site 2 of the formular please provide us the direct URL so we can take a closer look. In the meantime, please update both of your X and Cornerstone to the latest version to make sure that this is not an incompatibility issue.
Your current X (6.0.4) is not compatible with your current Cornerstone (3.1.3), please update both to the latest version X 6.1.4, Cornerstone 3.1.4
Updating Your Themes and Plugins
Remember to clear all caches (plugin, server-side, CDN, and browser's cache) after updating so that the code from the latest release is always in use. This will help you to avoid any potential errors.
Let us know how it goes,