Indoor cam not detecting motion even when waving arms and hands right in front of it.

Sorry to post another motion detection topic. I've looked through a bunch and didn't see my issue. My indoor cam is mounted in the hallway and at first was working flawlessly, detecting and recording every motion. Then my son snuck a girl into his room and got caught and when we checked the events, it hadn't picked up a thing and so I went on a wild goose chase trying to figure out if a shared account can delete footage (which is something he would do). After researching, it doesn't seem that's the case. But the camera on a full battery charge and RSSI -46 sometimes detects it when you walk by and sometimes not. It was working just 30 minutes ago but right now when I stood in front of it whaling my arms and hands, the blue light and 2 red IR dots never came on. I checked the events and nothing was recorded. Live view always works. So this appears to be an intermittent issue and I'm at a loss to resolve it. Firmware is up to date. Record Motion button is active. Motion Alerts off. Motion Detection is on and sensitivity is about 75% on the slider. Motion Verification has been troubleshot with both on and off. Nothing in Motion Schedule. Motion Frequency is Standard. Video Settings: Live View on, Tap Camera Preview for Live View off, Infrared Lights for Night Vision On, Video recording length 15s. Privacy Settings: Audio Streaming and recording On. Privacy Zones: None. Snapshot Capture Off. Any ideas? Could the cam be defective? I have 3 inside and 2 outside and this is the only one with an issue.