GPIO pins not responding

Hello,

I have been trying to achieve a remote toggle of GPIO pin 17 or 18, which I have done successfully in the past, but now it there is no response.

ArduCopter 3.6
Mission Planner 1.3.70

Pin 17 is high on boot, pin 18 is low, I am not sure why

Neither seem to respond to any settings I have attempted. I have confirmed that my receiver is functioning and channel 7 goes past 1800.

I don’t change these much:
CAM_RELAY_ON 0
CAM_TRIGG_TYPE 1
RELAY_DEFAULT 0

I have been playing with these:
CH7_OPT
RELAY_PIN
RELAY_PIN2
RELAY_PIN3
RELAY_PIN4

According to: Navio docs
I should use 14 or 15 to toggle pins 17 and 18

According to: Forums
I can use 17 or 18

I am not sure which is correct, but I have used 14/15 before successfully; neither is working currently.

I have tried:
CH7_OPT 34 (Relay2 On/Off)
RELAY_PIN -1
RELAY_PIN2 (#)
RELAY_PIN3 -1
RELAY_PIN4 -1

CH7_OPT 34 (Relay2 On/Off)
RELAY_PIN (#)
RELAY_PIN2 (#)
RELAY_PIN3 (#)
RELAY_PIN4 (#)

Where (#) is 14, 15, 17, 18, all without success: no change in either pin.

I have tried setting RELAY_DEFAULT 1, with those settings but there is still no change on boot (17 is high, 18 is low)

I have also tried CH7_OPT 35, 36 for relay 3 and 4, with similar settings to no effect.
I have also tried CH7_OPT 9, again, no effect.

Manually setting relay to high in Mission Planner results in an error.

Is it possible there is some hardware issue? If the UART port is broken I am willing to use RC outputs too, I just need any one pin to toggle when CH7 goes high. I am unable to diagnose and would appreciate some advice.

Thanks a lot!