If you want to make the joints passive, you should set: Actuation(none) - Motion (automatically computed). If actuated, you set to Defined by Input to accomodate the torque from a servo.
With your current setting Actuation(automatically computed) for the joints, a prescribed motion is required in some degrees of freedom in the mechanism to solve the kinematic states properly.
Try the new setting for the joints. I think it should work.
Regards / Juan