I am in the same situation, my Yaw servo is not controlled by APM2. I can control the rudder by TX, but APM does not make any action. I did put values as for roll, but still not action. Any idea, please?
The yaw gyro is not enabled in the fixed wing mode software although you can enable and see the raw data.It is not needed really as the model always has forward motion so the fin keeps it straight and torque has little efect on heading.In return to home mode the board uses aileron and elevator to control heading.