Hi @an-ron,
This is an ArduSub limitation of how the servo_n_* joystick button functions are implemented, not a Navigator-specific limitation - the same is true when using a Pixhawk, but with AUX pins 1, 2, and 3.
We’re planning to change that functionality to be more like the existing relay functions, where the pin is selectable, but for now it’s confined to those specific outputs.
Lights work fine for me on output 13. Have you configured that connection via the Lights page, or somewhere else?
Navigator does not yet have relay support.