Stickup Cam Battery (3rd Generation) Motion Detection Range very short

I recently purchased this cam to monitor a stairway in our home. Setup was seamless, signal strength in the 30-50 RSSI range, and most features seem to be working okay. However, as I walk down the stairway towards the camera, it does not start recording (blue light comes on) until I reach the very bottom stair (8 ft. directly in front of the cam.) I have tried tilting, changing cam height between 2 ft. and 6 ft, set motion sensitivity on max, and advanced motion detection is on, but the detection range is never more than 9 ft. or so. I have even come down the stairs wildly waving my hands, but that makes no difference. What am I missing??