As a security device, Scout requires an encrypted Bluetooth connection. In this case the Bluetooth connection has not been correctly established.
This can happen if the Bluetooth connection is forgotten via your phones Bluetooth settings. To correct this, remove the Scout from the Knog app, your phones Bluetooth list and the Find My app and perform a factory reset. Then set the Scout up again in the Knog app as a new device.
Do not attempt a factory reset while your Scout alarm is armed.