Arming with rudder left (not right)

ArduPlane Plane 4.0
1

Installed Omnibus F4 Pro v3 in my first 4ch plane today (have been flying in wings for years), and strangely will only arm if I push rudder left on stick. My Taranis has theOutput for ch4 in normal direction (not reversed), but rudder was going wrong way, so I checked the Reverse option for the Yaw channel on the RC Calibration page in MP, so rudder surface direction is now correct, PWM signal from stick increases with right rudder (ch4in in status page), but strangely it now arms with left rudder and not right.

I am running 4.0.3rc2 but downgraded to 4.0.2 release and still same issue.

2

OK, so quick update:

I unchecked Reverse on the radio calibration page (for yaw), and instead enabled reverse on the Servo Output page (for ch4), and now the arming is happening with rudder right as per normal.