Why does the camera stop running?

Why does the camera stop running and display an orange banner?

Some time you see the live camera stop running and the camera button turned gray. The app also displays an orange banner telling why the camera is stopped running.

The reason is: When the camera is running and something (e.g. receiving a phone call) interrupts or uses the camera / microphone, then the AiCam app will stop the camera. Normally the app will try to resume running the camera after the interruption is ended, sometime just after several seconds, sometime after several minutes, depends on how long the iOS system blocked the using of the camera / microphone.

For better stability you can use Guided Access mode. Please see this FAQ.