Was a solution ever found here? I have a similar issue to this. While walking backwards my character seems to turn slightly one direction or the other. Starting the game with the forward direction at x=1, y=0, z=0, walking forward nothing changes. Walking straight backwards and X bounces around 0.95-0.97, Y from 0.25-0.27. I stop walking, it instantly goes back to 1,0,0.