why unscented kalman filter changes the results of unrelated blocks?

I am trying to use unscented kalman filter to represent human pilot processing of sensory information. i am using a simple aircraft model K/s (motion model) and a delay to represent visual processing (sensor model). the motion model and sensor model give reasonable results before adding kalman filter, but there results blow up after adding kalman filter. i am not sure how kalman filter can affect the results of systmes not related to it. attache below some pictures and the model.

Before adding kalman filter

---------> results of the motion model

After adding kalman filter

---------> results of the motion model

--------> unscented kalman filter parameters