Affects Logger Pro and LabPro, not LabQuest.
If you turn off the default zero at collect option for the rotary motion sensor, and then zero the sensor in some position, and the sensor is moved before data collection begins, then the zero will not be correct. The more the sensor moves before data collection, the more the zero will be off.
Workaround: design your experiment so that you can use the zero on collect mode. The zero will not drift during data collection.
LabQuest does not have this problem.