It might be due to the improper up-gradation of the Cornerstone plugin. It seems that you have already updated the theme to its latest version i.e 8.1.5 whereas the Cornerstone is still in 5.1.4 version. I would recommend you update the Cornerstone to the latest one by following the below steps.
- Delete the Cornerstone existing one
- After deletion of the Cornerstone, please use the link in the dashboard to automatically install the Cornerstone.
If that does not resolve the issue, I would suggest you troubleshot a few common issues on this.
2.Child Theme Related issue
3.Theme Update related issue
If you discover that an issue is coming from a custom code or 3rd party plugin, kindly consult with a developer or contact the plugin author. Please note that we do not provide support for custom codes and 3rd party plugins.
If none of the above helps and you are still getting the issue, please provide login credentials for your site in a secure note to examine it further, including:
– WordPress Site URL & Login URL
– WordPress Admin username/password
To create a secure note, click the key icon underneath any of your posts.