GetHumanPose and SetHumanPose in Update

I’m developing bone constraint system for Unity Mecanim.
However, I had a trouble.
I used HumanPoseHandler.GetHumanPose and HumanPoseHandler.SetHumanPose in Update method.
Then, character’s position was changed when character’s initial position was not (0, 0, 0);

This is my code.

void Awake()
    {
        if (animator == null)
        {
            Destroy(this);
        }
        poseHandler = new HumanPoseHandler(animator.avatar, animator.transform);
    }

    void LateUpdate()
    {
        poseHandler.GetHumanPose(ref pose);
        pose.muscles[35] = x;
        poseHandler.SetHumanPose(ref pose);       
    }

I got the same trouble 3 year after …

this code made the character move for no any reason

poseHandler.GetHumanPose(ref pose);
poseHandler.SetHumanPose(ref pose);

I have to manage the position by myself to fix the trouble

Hi, I have just come across same issue, Getting and Setting the same pose right after moves the character. In my case is the hip joint which gets translated.

Can anyone from Unity explain this behaviour? Thanks