Stick Up Cam Battery not Detecting People (Gen 3)

Hi All, Just installed a stick up cam battery. It points out our sideyard into the street. Our goal is to record activity on the sidewalk in that area. See attached screen shots for the area its pointed at, and a shot of a person walking on the sidewalk. The cam has no problem detecting and alerting for a car that drives by, but regardless of how we set the motion settings (we've tried just about every combo of sensitivy and frequency, etc.) it will not alert when a person walks by. Even though the people are closer to the camera than the cars it alerts on. We have tried it with motion sensitivity set to high, and detection set to Frequent, and with Motion Verification both on and off. The motion zones covering these areas are on. Again, we can walk in front of the camera on the sidewal and jump up and down and wave our arms, and no alert. But if a car drives by 10 feet behind us, it will alert . Reminder that Stick Up Cams do not have customizable motion zones or people only mode. Any thoughts appreciated. Is it possilbe our camera is defective? Or have we just exposed a flaw in Ring's motion detection algorithms.