Hi @Kleech,
I checked and your cornerstone builder is working properly. But since you mentioned about essential grid and slider, then I checked it and confirmed the issue, and it’s because of internal server error.
jquery.js?ver=1.12.4:4 POST http://www.leechcreative.com/cornerstone-endpoint 500 (Internal Server Error)
I installed Debug Info and saw that your PHP version is old, please update your PHP version at least to 5.6 or greater. If you’re on shared hosting then this will likely to happen too. The more active software, the more resources it will use, even the Slider alone recommend at least 256mb. But that’s just my assumption since your limit is already set to 256mb, I’m not just sure if you’re on shared hosting or not. Because shared hosting will not allow you to change the limit even if you set it yourself.
Please do this so we can find the details of the error 
- Login to your site through FTP or File manager and edit
wp-config.php
- Change this line
define('WP_DEBUG', false);
to this new lines
define('WP_DEBUG', true);
define('WP_DEBUG_DISPLAY', false);
define('WP_DEBUG_LOG', true);
Save it.
-
Load the cornerstone builder again, but this time make sure the slider and grid are active (this is not about fixing the issue yet, but just getting the information). Do this 3rd step at least two times to make sure the error is triggered.
-
Through your FTP or File Manager, download the file /wp-content/debug.log
and provide it in a secure note (you may use file hosting for the debug.log and just provide the download URL).
We’ll see what’s the actual error 
@outer_net, please start a new thread and provide your site’s URL and admin login credentials in a secure note. I need to gather information first, there are many contributing factors so it’s too early to say that it’s due to updates 
Thanks.