A “Signal Loss Alarm” means that the sensor has not automatically communicated with your device in the last 20 minutes.
Check that your Libre app or FreeStyle Libre 3 app on your smartphone is within 33 feet of the sensor.
If you continue to see a “Signal Loss” message please complete the quick and convenient online sensor support request form, or contact Customer Care Customer Care which is available at 1-855-632-8658 7 days a week from 8AM to 8PM Eastern Time; excluding holidays.