Can please check the version of X that is installed on your site? Since you have updated Cornerstone to the latest version, your X version should also be updated since it will cause an incompatibility issue if only one of them is updated.
The latest version of X to date is 7.1.2.
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.
Very strange. I have the most recent version of both cornerstone and X theme and still not seeing those options. I even uninstalled cornerstone and reinstalled. I just went ahead a created a css class.
.everydevice { background-repeat: repeat !important; background-size: auto !important; }