Garmin Fenix 6 Pro - External Cadence Sensor - Outdoor ride

I've recently decided to connect my Wahoo Cadence sensor to my Fenix 6 Pro watch when riding outside. 

After every ride, it only shows cadence at a random time (See image below)

I don't have this issue when riding at home with my Wahoo Kickr Core 

I've checked many forums, and it says to verify the battery. I've decided to swith to a new one, still have the same issue. Was wondering if other people have the same problem as me. 

Thanks for the help!