HR Drop with HRM-600 and Edge 840

Hello

during my first ride with the new HRM-600 I noticed some drops in the HR - which I did not experienced during my following 2 runs using my F8 - also connected to HRM-600.

https://connect.garmin.com/modern/activity/19221500935

HRM 600 is paired securely with the Edge 840 using BLE. (same as F8) 

FW: HRM 600 : 5.2 / 840 : 27.13 / F8 : 15.31

It also lost 15% battery during this first 4h ride. (100->85%) - including an extra hour wearing it before starting the ride itself.

In terms of how it feels wearing it, it feels just the same to me as HRM-Pro. It just weird to see a "led" thought your clothes before your start your activity :D