I have one of these with electron retracts.
It worked fine until i selected s-bus as the input rather than servos.
The brakes and steering work fine, but i have my gear on channel DG1 ( channel 17) and the LG15 only sees 2 us of movement when i flick the switch.
When i change the gear channel to for example channel 15, the LG15 sees that and the gear moves.
There is something odd about the two binary channels on the 18mz, its odd because the powerbox sees channel 17 normally, and activated the gear, just not over s-bus