ICM42688 Accuracy reading, Meaning? Interpretation?

- We are using the ICM42688
- We are using the INVN fusion algorithm for configuration of the IMU and calculating orientation measurements.
- We use the function invn_algo_asf_process to output to a variable of type InvnAlgoASFOutput
- We check the accuracy values acc_accuracy and gyr_accuracy.
- The value acc_accuracy is always zero.
We want to know:
1. Is acc_accuracy supposed to always be 0?
2. What does the actual value of gyr_accuracy mean? It says accuracy from 0 to 3. But, what does that mean? (e.g. When is the accuracy "enough"?)
3. On rare occasions we only get accelerometer readings. I have used a logic analyser to identify that the values coming from the FIFO are reporting with the largest FIFO packet size but the gyro readings are "invalid". There doesn't appear to be anything wrong with any of the values written to or read by the INVN system.