Flag outside motion zone, creates incident ONLY at night

We have a flag on our front steps and I've set the motion zone to exclude it which works fine during that day. At night however the flag motion sets off a recording/incident and triggers an alert which is becoming a pain. Since this is working during the day, I assume the issue must be due to the sensor/IR not aligning to the motion zone. Anyone have a clue on how to correct this or if this is a known "challenge"?