Thanks for writing in! A white screen usually means a PHP fatal error. Enable your WP_DEBUG mode on WordPress by editing the following line your wp-config.php file can be located inside the root of your WordPress installation.
Then try loading Cornerstone again to see if you're getting any errors on the page.
This issue could be due to various factors. First check your PHP version running on your server and make sure to use a version PHP 5.6.x or later. If you're not sure what your server configurations and settings are, install a plugin like WP-Serverinfo (https://wordpress.org/plugins/wp-serverinfo/) and check your server info by head over to Dashboard -> WP Serverinfo area.
Also it could be that you're running out of your allocated memory, in that case you can try adding the following code into your wp-config.php file.
Add the following lines into that file.
define( 'WP_MEMORY_LIMIT', '512M' );
define( 'WP_MAX_MEMORY_LIMIT', '512M' );
You can add it before the line
/*That's all, stop editing! Happy Blogging. */
Let us know how it goes.