The latest version of Cornerstone is 3.2.5.
Either you have an outdated version of Cornerstone, or your Cornerstone Advance Mode is not enabled.
That is a feature introduced on Pro 2.1.0 / X 6.1.0 / Cornerstone 3.1.0 release. Read more about that here.
You can also check what are the latest versions on that changelog page.
Hope it helps,