I checked the specs for my Norwegian 116i M Sport. It has neither servotronic nor active steering. That is why it works perfectly in all driving modes!
The active steering has a unit that works a bit like a differential that can add or subtract steering angle with an electric motor. It can make the steering quicker at low speeds and slower at high speed. It can also make corrections if a slide gets out of hand. I personally don't like interventions like that. It is better to let the driver be in control of the car.
I don't know how the default steering and servotronic are implemented. I have the impression that both are direct rack and pinion setups with electrical power assist on the steering shaft. Maybe one is "stupid", and the other one is "clever", trying to adapt the amount of assist depending on drive modes and speed.