If the iPhone is out of Bluetooth range at the time the alarm was triggered, then no notification will be received. The Knog app also needs to be open in order to receive notifications (it’s OK if it is running in the background).
In a free field environment (line of sight) the bluetooth range can reach a maximum of 60-100 meters. In most instances you will see a range of 30-50 meters.
Indoors, or in an environment with structures between your phone and the Scout ( for example if you are indoors and the Scout is outdoors), the range will reduce to 10-30 meters in most instances.