I purchased a new venue 3 in the past year and a half that I have since thrown away because my pulse would skyrocket (140+) on the watch while I'm cardio mode. Only going 2 mph at a zero grade, so it wasn't me. Cleaned watch back and wrist several times. Moved along wrist area to find stable measuring point with no luck.
I then purchased a venue x1. Loved the colorful screen! The square screen also allowed me to easily view more data, too. Unfortunately, same unstable, high pulse measurements even after calling Garmin support for help. I just gave the watch to my daughter. As the mother of two, she might have a high pulse and be able to use it. Because I LOVE the Connect software, I just decided to try my luck a couple of weeks ago with a new Garmin Instinct 3 thinking that with a different sensor that I'd have better luck with the pulse reading. Nope. I've thrown so much money at Garmin Smart Watches only to be disappointed over and over. It's so sad that their great software has to be paired with, in my experienced opinion, hardware that is so well engineered with such bad sensors. Not sure if they took data while they did live and HALT tests, but you need to try harder, Garmin.