Not disputing you, but for clarity you may want to specify the affected models.I had a vivoactive and a forerunner. There were problems for almost a year with the heart rate tracking, Garmin even said that and wrote a trouble shooting page about it. Only their tips didn’t work. If I remember correctly there were more affected models, not only vivoactive, forerunner and venu 3 but also some other watches for outdoor.
Forerunner is a product line with myriad models since the first release in 2003.