Adjusting cruise throttle % creates osscilations in TECS (Pitch and Throttle control)

I have throttle nudge turned on. When I change the throttle to particular values it can cause the TECS to go crazy with the pitch and throttle control. Here is a log clearly displaying this:

Having the servos and escs driven up and down like this puts them under undue stress and could cause a failure so I’m very keen to get to the bottom of the issue. How would I go about narrowing down the cause? What would cause the oscillations in the TECS controller?

The plane otherwise performs very well. It has had the same issue for Arduplane 3.5, 3.6 as well as possibly earlier versions. Vibration levels are low. GPS switching is disabled and the airspeed sensor is calibrated, digital and appears to be accurate.

I have reflashed the pixhawk back to default and re-tuned and also tried defaults and the same thing happens. I have also tried different ESC timings as well as changing my taranis gimbals to make sure the noise I previously had on the RC3 input wasn’t causing this.

Bump! ___________________