Battery was dead on arrival but after replacement I was able to pair the sensor with every app I use : tacx, strava, running... and it is working fine. Doesn't seem to work with my garmin explore though. Still, I am very satisfied.
I use the belt with my fenix 5 . It connected fast and easily. I used two times so far in my running training, so far satisfied. Very good "grip" on my chest, it does not slip!!