MTF01 optic flow sensor, no compass and the vehicle climbs uncontrollably

I’m using a Radix 2HD flight controller without GPS for indoor navigation, along with an MTF-01 optical flow sensor. My setup does not include a compass, and as far as I know, the flight controller lacks an internal compass as well. The video guide provided by MTF for ArduPilot suggests enabling the compass for EKF3 velocity, but I’ve disabled it due to the absence of a compass.

The issue I’m encountering is that in Alt Hold mode, the drone starts to ascend uncontrollably. How can I resolve this problem?

Any help is greatly appreciated.

Best,
Satya