Throttle drops in non-MANUAL modes

Hello everyone,

I have set up a gas plane using Pixhawk and Plane 3.7.1.

I have trimmed my throttle to hold the desired idle level, while in MANUAL mode.

However, when switching to STAB or FBWA, the throttle drops by a small but significant amount. The following screenshots display the MANUAL and STAB response.

THR_PASS_STAB is 1 but the problem is not in the cutoff range.

Thanks in advance.

Parameter file and log can be provided (not at hand right now).