This one may be one of those simulation issues where at a high taxi speed, the aircraft will not turn - almost to simulate the nosewheel skidding. For a 172 that’s very fast. Keep your taxi speed around 10 knots. In the real 172, RPM should be at 1,000 or less for taxi, but I honestly often pull even lower than that just to keep the speed down and keep from riding the brakes, another thing to be aware of during taxi.