Hello There,
Thanks for updating in! Since we do no have any access to your site, we cannot investigate it. All we can do is hit and miss kind of way hoping it maybe resolve. The Cornerstone’s custom path won’t matter. X/Pro theme would run without issues by just using the default x path having a permalink of …/x/#/content/{123}/. You can try and add anything and it should still work in a normal WP installation. In your case, this is different because there could be some factors that created the issue throwing a conflict error on the page. It could be by a custom JS error, a file could be corrupted or an error 403 or 500.
Please do the following:
1.) To make sure that no files were corrupted, please re install Cornerstone. Please go to the plugins section and deactivate Cornerstone. Hit the delete button to totally remove Cornerstone. After doing that, please go to X > Overview so that Cornerstone will get re installed automatically.
2.) To find out if there are JS error while you are editing in Cornerstone which may have resulting to getting a conflict error, please use your browser dev tools. If you are using Chrome, you should be able to see any JS errors in the console if there are any. To know more about Chrome Dev Tools, please check this out: https://developer.chrome.com/devtools
3.) For any 403/500 errors, you may find this in the console (if there is an error):
https://vendini.staging.wpengine.com/cornerstone-endpoint 403 Forbidden Error
https://vendini.staging.wpengine.com/cornerstone-endpoint 500 Fatal Error
It means that the request returns 403 Forbidden or otherwise, and it’s mostly related to security. Please contact your hosting provider and see if they can disable the security or exclude that URL and all requests (all payload related to that URL ) from your security rules.
Please let us know how it goes.