Blind Spot Detection malfunction

I have a left hand drive Portofino with the ADAS system. The Blind Spot Detection, which should indicate whether it is safe to overtake or to go back to the right lane is peculiar. On the right (passenger) side, the yellow triangle comes on when the car on the lane you want to go into is quite far away. In other words, it is safe to move over if it is not on. However, on the right (driver's) side the triangle comes on ONLY when the car in the lane you want to move into is right next to your car. You CANNOT rely on moving to overtake because the light is not on as the triangle will come on only when the other car is really next to you.
Is it normal that there is such a large difference when the triangle on the two sides starts flashing: the driver's side when the other car is VERY close and the passenger side when there is ample distance.
It could be that the radar on the driver's side in my car is not properly adjusted. I asked the dealer and he did not know anything about it, nor how to measure the angle or distance. He said ADAS was very new rolleyes.
Could someone who has ADAS (does not have to be in a Porto) let me know whether their driver's side triangle flashes only when the car is very close or at the same distance as the passenger side distance.