I've had a few Phantom 4 Pros, and lost a couple so I have more controllers than aircraft. All are P4P v2.0. I have two 'plus' controllers with the built in screen. One is a GL-300K and one is a GL-300E. They appear identical physically. I don't know the difference. Only the K version links with my Phantom 4 Pro V 2.0's. The E will not. What's going on?