Sonar range check after flow install

After installing a flow camera i get a sonar range check that i can clear only raising the aircraft above 50 cm.
This is a bit weird because i had the range finder before the flow and never asked for a pre flight check. My minimum height is set correctly and it doesn’t ask for check if i disable the flow i just installed.
Running 3.6.8.
Range finder is a Lightware SF11/C
Do not understand why it asks for check only with flow enabled.

Because optical flow requires good sonar/range finder data when the optical flow is enabled, an additional pre-arm check is enforced.

While the vehicle is disarmed you should lift the vehicle straight up to at least 50cm but no higher than 2m (if the rangefinder sees a distance of over 2m you will need to restart the flight controller).

The error message when arming fails this check is “PreArm: check range finder”

This check can be disabled by unchecking the “Parameter/Sonar” arming check.

Great, thanks.