Thanks for asking.
I checked the website and it seems that you are using fairly old version of X Theme 5.2.3. I can also see that you are using Cornerstone version 3.3.8. To avoid any compatibility issues, please update X Theme and Cornerstone to the latest version 6.4.6 and 3.4.6 respectively.
Here's some resource that you can refer:
For the changelog: https://theme.co/changelog/