Thanks for writing in.
Would you mind double checking if your X, Cornerstone, and Revolution Slider versions are updated?
Here is a link for a details information on how to do an update:
Please remember to clear all caches when updating so that the code from the latest release is always in use. This will help you to avoid any potential errors or any unexpected display issue on the site.
If everything is updated and the issue persists, please try testing for a plugin conflict. You can do this by deactivating all third party plugins, and seeing if the problem remains. If it's fixed, you'll know a plugin caused the problem, and you can narrow down which one by reactivating them one at a time.
In case you are getting the issue, please provide us with the admin access to your site in a Secure Note (key icon under the replies you post/posted):
Let us know how it goes!