Optical flow example data [indoor local position estimate]

Could someone please give an example of a valid optical flow messages received by their px4?
I’m using a PMW3901 optical flow sensor connected to an RPI, the Optical_flow_rad messages are sent using mavlink to achieve an indoor local position estimate, which works just fine for the first 2 seconds of moving, then the failsafe activates because it loses “the local position estimate”.

those are my logs as timestamp, flow_x, flow_y

really appreciate any help.