Plane not climbing in autotune mode

Trying to run Autotune in my APM 2.0 but coming up against a strange problem. When I switch from manual control to autotune, the plane will not climb. I try to do the climbing and diving as instructed but it only dives. Pulling back on the stick maintains level flight only.

It rolls left and right OK.

My trim in manual flight is marginal, and there is some sub-trim for the servos but not much. The plane has been calibrated level.

Any ideas?

When you’re in FBWA mode and just pitch the plane up and down by hand, does the elevatrix counteract the movement appropriately? Meaning, when you put the nose down, the elevator should go up to counteract the movement, not just try to stay parallel to the ground (which is actually down…I got that backwards in my mind once and the result wasn’t pretty…)

Yes, the elavators move in the correct direction to stabilize the plane in FBWA mode.