I don't know if this has anything to do with it but since someone just shared this with me I thought I would pass it on here.
From here: DX8 to AR6100 issue resolved - need to bind correctly!
This person discovered something that is slightly different then the manual suggests. The DX8 manual states the following procedure:
You must bind the receiver to the transmitter before the receiver will operate.
Binding teaches the receiver the specific code of the transmitter, so it will only
connect to that transmitter.
1. To bind an AR8000 to a DSM2 transmitter, insert the bind plug in the BATT/
BIND port on the receiver.
Note: To bind an aircraft with an electronic speed controller that powers
the receiver through the throttle channel (ESC/BEC), insert the bind plug
into the BATT/BIND port in the receiver and the throttle lead into the throttle
(THRO) port. Proceed to Step #2.
2. Power the receiver. The LED on the receiver will be flashing, indicating the
receiver is ready to be bound to the transmitter.
3. Move the sticks and switches on the transmitter to the desired failsafe
positions (low throttle and neutral control positions).
4. Press and hold the trainer button while powering on transmitter.
5. The system will connect within a few seconds. Once connected, the LED on the
receiver will go solid indicating connection.
6. Remove the bind plug from the BATT/BND port on the receiver. Power off the
transmitter and store the bind plug in a convenient place.
From this thread this person does step 4/5 differently. Instead of letting go of the button once the bind light is established the button is held until the DX8 resets. I've never done this but I'm going to rebind all my planes in this fashion and see if this makes any difference with the 6200s I have. Worth a shot I guess.