It's been now several weeks and the heart rate is wrong. Consequently several measurements and fitness ratios are also wrong. I had various FitBit devices over the last 4-5 years, never had such a problem. It is disappointing that there is no effort to correct the issue in one of the high end products of the company.
Some examples: 3 hour walk, almost 18k with elevation and the HR seldom increased over 100 beats! laughable. 30 minutes HIIT session, all sweat and dying and it shows 90 HRBs... This is outrageous
