Post edited to include correct image.
I have an HRM-Pro Plus paired with a Fenix 6X Pro.
When I'm using it on my treadmill it seems to stay really low initially (until the 5-7 minute mark) before going way above what I would expect my HR to be for the given effort. I've been testing it on runs where the speed remains the same for the whole run. I would expect around 127-130 bpm once warmed up and I've had it go up and down like a yo-yo and once to 172bpm.
Below is today's chart. It went way up and when I switched to just the wrist based reading at about halfway that settled around 128-130bpm and stayed consistent, rising a little as I got a bit warm.
I don't seem to get this issue when running outside very often and when it does happen it settles back fairly quickly.
I keep it clean in line with Garmin's methods. The battery life according to the app is good and I use ECG gel on the pads. The strap is about 16 months old.
Any idea? Thank you.
