different force results between staticFvMesh and dynamicMotionSolverFvMesh in DTCHullMoving tutorial

I am testing DTCHullMoving tutorial case about staticFvMesh and dynamicMotionSolverFvMesh with ramp setup as follows:

dynamicFvMesh   dynamicMotionSolverFvMesh; //staticFvMesh;

motionSolverLibs (rigidBodyMeshMotion);

motionSolver    rigidBodyMotion;

report          on;

solver
{
    type Newmark;
}

accelerationRelaxation 0.4;

ramp
{
    type    linearRamp;
    start   1000;
    duration 1;

}

At a first glance, I expected that the results from staticFvMesh setup would be the same as the results from dynamicMotionSolverFvMesh with ramp setup which has a long time to activate because the body is not moving and the mesh flux is zero. But the results are different.

I did not touch any setup other than the dynamicMeshDict as above.

Any comments will be helpful.