I've had problems from day 1 with these new sensors, but I've had it working for quite some time now regardless. Initially I couldn't get it to pair at all:
https://forums.garmin.com/showthread.php?107509-New-Speed-sensor-no-lights-will-not-pair-no-activity-at-all-from-sensor
And I ended up getting a new sensor under warranty. After about 10 battery pulls, I finally got it to pair up. It had worked for months, but tonight it stopped pairing altogether. The sensor is working correctly - I'm running Zwift and TrainerRoad, and they both find the sensor and pull the speed from it with no problem at all. I just can't get my Edge 500 to pair with it anymore.
I have the bike profile set to "Speed and Cadence Sensor", which has always worked in the past. I've tried setting Spd/Cad to "No" then "Yes". I've also tried setting to just speed. I've put a new battery in the sensor, though since it's working with my ANT+ dongle devices I don't think that was the issue anyway.
I have two other bikes with GSC-10s on them and they work just fine - it's just that the Edge doesn't seem to want to talk to the new sensor anymore after switching bike profiles.
Any insight would be appreciated.