Pedometer and lp quaternions error

Good morning everyone!
I'm experiencing some issues with the MPU9250 pedometer and lp quaternions:
when reading the data respectively from the DMP and the FIFO I get incoherent data from the pedometer (step count growing much higher than the number of steps) and the quaternions (the last two elements perfectly match the quaternion I calculate myself on the acquired sensors data, while the first goes randomly high and the seconds is always 0).
Any suggestions?
Thanks in advance!