PX4 Vision optical flow not working

Dear all,
I am trying to use PX4Vision indoor without GPS. I changed EKF2_AID_MASK to optical flow only. PX4Vision uses PMW3901 and SF20/C Lightware Lidar on I2C. In mavlink inspector I can see DISTANCE_SENSOR and LOCAL_POSITION_NED topics working. I take off in Position Mode but drone drifts on the right with high velocity so I have to switch back in altitude in order to take control. In other words it is not able to keep hovering. Room is illuminated and the floor has texture.

Can you help me in solving the issue?
Thanks a lot and regards

Have you any suggestions to help me? It is an important project and I need to fly indoor.

Thanks a lot,