You must have a strong enough cellular or wifi connection to receive an alert. If you do not have a strong enough cellular or WIFI connection when an alert is sent, the alert will be queued for a limited time and once your device has established reconnection it will become available. Examples of when your device is offline:
- device is in airplane mode
- cellular or WIFI turned off
- out of range of a local cellular tower or wifi base station
- in dead zones where the cellular or WIFI signal is unavailable