Hi @ChalieC with these being a wrist based device, the hands need to freely swing to get the steps recognized. So, why not put the Fitbit in your pocket while on the treadmill if you're trying to get those steps in.
Best AnswerThis happens to me too. As @Odyssey13 said, the hand needs to swing freely with these wrist worn devices so if you hold onto the bar when on the treadmill (as I do) steps and distance won't be calculated properly. Unfortunately, if you use the solution of putting the device in your pocket you lose the heart rate monitor. In my case, in addition to the Versa 3 I have an old Fitbit One device that was made to be worn on the waist. Although Fitbit does not recommend it, I wear both devices at the same time when I'm on the treadmill or stationary bike. When I sync the devices, the steps are synced from the One and the heart rate data is synced from the Versa 3. I didn't have to do any special setup for this to work but if you have a second device and try this solution your mileage may vary.