You are running esxtop to analyze performance issue of a particular virtual machine and cannot expand GID.
This is by design of the esxtop command. In vSphere 4.x, there is a maximum character limit of Seven (7) characters in the esxtop expand command. In vSphere 5.x, this maximum was increased to a limit of Eight (8) characters in the esxtop expand command.
The workaround this issue, use the Numeric Keypad (numpad). Press 2 or 8 on the Numeric Keypad to move up and down the selected group. Press 6 to expand the selected group.