Any chance that the motion time is being changed? 12 seconds is way to short to capture all the motion. A good option would be to continuously record until the motion stops.
Alert clips uploaded to the cloud are limited to 12 seconds every 5 minutes per alert in order for Wyze to be able to provide this service for free. If you want continuous motion recording, you can install a microSD card in the camera which will capture motion until it stops (or the card is full).