How to fix motion detection that is not working on smart cameras and sensors

This is a useful cross-category article because both cameras and sensors share this intent.

1. Check whether the problem is missed events, delayed events or no events at all.
2. Review motion zones and sensitivity settings.
3. Confirm the sensor or camera has the right placement angle and detection distance.
4. Inspect battery health and low-power modes.
5. Test alerts and automation triggers separately.

Cross-links well across cameras, doorbells and motion-sensor pages.