FniV -> Option 1 -> Set to 3
The problem with this is that your grip does not have a AF-ON button, so to fix this you can swap the AF-ON and the * buttons
FnIV -> Option 2 -> Set to Enabled
This will cause the * button to lock focus and the AF-ON will Lock Exposure adn zoom out on image preview.
Of course the problem here is you can not Lock Exposure when using the grip in portrait.