The 2386 is AcuSense, so if you have the filter set to Human and/or Vehicle you shouldn't get a false trigger when the IR cut filter moves over the lens. Or you could just increase the dwell time for the intrusion alert a little. The purpose of intrusion is that the trigger is when a target moves into the area and stays in the area for a pre determined time.
It's the main feature of the newer cameras. Without filtering to either human or vehicle every moth, shadow, blowing leaf is capable of triggering an event. I usually set them to human only - I'm not really interested in the presence of a car.