How to Efficiently track Orientation of a Robot using DMP EMD 6.12

Hello people,
Im trying to track the orientation of a Robot, whose orientation has to be tracked and displayed on custom developed PC app in 3D.
I used the Motion App v4.2 version and was able to obtain the Quaternion data from the DMP FIFO. Then i migrated to Motion Driver 6.12. But to my surprise i was able to observe a drift in Qz value over a long period of time. Is this expected in the latest 6.12 Motion Driver? or am i missing to perform any calibration step? Can someone please help me.