No heart rate data using Fenix 6 Pro as sensor

I can connect my Fenix 6 Pro as a heart rate sensor, but my Edge 840 fails to connect to it and receive data. The Fenix is in sending mode and it works with other devices, for example the strava-app on my phone. Just got my Edge a few days ago and it worked once, I think before it upgraded itseld to 20.19. Any avice?