I assume you are using the single-shot mode in the CraftAR app. There might be a problem while taking the picture, which might be causing the camera to stop, and then, not returning the picture, so the search is not being processed. Please, try on other Android devices and see if it works normally. Also, you could try using the finder mode, and see if the behaviour is the same. It would also be helpful if you send us the logs from your Android device while this is happening, together with the OS version and the device model.
Regarding the camera not working:
The camera of the device sometimes gets blocked, when that happens the only thing you can do is to restart the phone. There are multiple reasons for this to happen, but anyway, that’s an OS problem. It happened to me with any app that uses the camera. The camera can crash mainly in two different ways:
1- When the access to the camera is blocked (camera.open() fails)
2- Camera opens but does not work.
For the first case, the CraftAR SDK triggers an error showing a Dialog advising that the camera could not be opened, and then closes the app. If you want to modify this behaviour, override the method onCameraOpenFailed() in your CraftARActivity.