I am very bummed out. I first tried using a wahoo Tickr heart rate monitor. I was able to pair it to the Edge 520 but heart rate is not displaying. I asked a question in the Forum and was told the problem is with Wahoo. Therefore I got a Garmin Pro heart rate monitor. It works great and connects with zwift. Also, I am able to pair it with the Garmin Edge. However, it does not display heart rate. Yes, I have the heart rate monitor on. I did test it with another device that shows my heart rate.
Also, I have paired my Assioma pedals to the Garmin Edge 520 and it works great!