Ardurover obstacle avoidance issues


I’am running an ardurover 4.0 on pixhack board and have some issues when it comes to object avoidance(with bendy ruler).
So the rover is just a basic rc car with normal steering using servo.

For a Proximity Sensor/Rangefinder i am using a front facing Maxbotics LV-EZ0 Sonar connected to pixhawk via UART( also rs232-ttl converter was needed and i have added capacitor to stabilize current as stated in documentation ).
Everything seems fine, the proximity viewer in mission planner works good. But when it comes to driving auto or guided it is acting weirdly, it drives in slalom or circles but it always gets to the target finally.
I have made several tests with different sonar locations on the front and it was mainly the same with minnimal differences.
Test that made me go crazy was when i turned off obstacle avoidance and turned on the option where it just stops in front of obstacle - and it worked just fine!

Does anyone have any idea what can be a problem?
Also i cannot see obstacles in mission planner but i should as it is turned on in parameters.