When rotating the motion tracker somewhat faster, it fails to output the orientation correctly.

Most likely the orientation errors you are reporting were caused by exceeding the specified range of the gyroscopes. The orientation cannot be estimated correctly when the gyroscope range is exceeded. In dynamic situations, the gyroscopes are the source of the most important information for the orientation estimation algorithm. When exceeding the measurement range of the gyroscopes, the orientation filter will ignore gyroscope data and instead use accelerometers and magnetometers. Because of the high dynamics of the situation the sensor is in, the information from the accelerometers and magnetometers will be inadequate for orientation estimation.

If it is likely that the maximum range of your sensor is exceeded during your application, you should consider using a sensor with a larger gyroscope range. Available gyroscope ranges are 150, 300 and 1200 degrees per second.

The Status byte will reflect an out-of-range condition by dropping the XKF valid bit to 0.