Hi there,
Please try to install and run Transient Cleaner (https://en-ca.wordpress.org/plugins/artiss-transient-cleaner/).
1. Install Transient Cleaner
2. Navigate Dashboard -> Tools -> Transients
3. Set Clear Expired Transients -> Enable
4. Select Run Now
5. Set Remove All Transients -> Enable
6. Set Remove All Transients -> Optimize Afterwards
7. Select Run Now
8. Recheck your Cornerstone for functionality
If it doesn’t help, please provide us with your admin account & website URL so we can take a closer look.
Let us know how it goes.