Smoke / Co2 Listener not passing the alarm to base station

Trying to set up a smoke /co2 listener without success. When in test mode, I trigger the test mode siren and the Ring sensor reacts by flashing the red rings. So, the sensor seems to trigger but that is not transferred to the base station. The app and base station never detect the trigger. I contacted Ring support who went through a bunch of troubleshooting steps including resets and eventually sent me a replacement listener. Same exact result with the replacement. What is going on with this? Any ideas would be great. Thank you! Hish