Portal Drive - SP15 KM UI Feature not working

We've recently installed SP15 in our sandbox environment (from SP14). One of the features we are currently testing is the KM UI command for users to map to Portal Drive.

Unfortunately, the documentation is rather slim on this new feature. It tells you:

"By default, the UI command is not visible in any iView. In order for users to be able to use the command, you must add the mount_PortalDrive user interface command to the corresponding command group in the KM UI configuration."

I added the "mount_PortalDrive" UI Command to the correct command group and it's not showing up. I even restarted our sandbox environment and still nothing.

Any ideas as to why this is happening? Did I miss a step some where? Thanks.