We found that F1 filter did not seat on the release sensor as we posted on klog#15400. One of the sensors was not touching on the bottom of the F1 filter because a cable clamp distubed. ( Please see the following picture)

Additonally, we found that F2 was not seated on the sensor because the F2 was swinging (sorry no picture). So, This would be a reason why two of the F2 sensors were not blinking.