First of all please kindly make sure that you have the latest version of X and Cornerstone.
Secondly, purge cache if you have such a plugin.
Then, check for 3rd party plugin conflicts by deactivating all plugins except the Cornerstone and see the result. If it is fixed then activate plugins one by one to find the plugin responsible for the problem.
Lastly, if you still experiencing the issue kindly get back to us with the URL/User/Pass of your WordPress dashboard using the Secure Note functionality of the post to follow up the case.
You will need to also mention the name of the page which you experience the breadcrumbs problem.