I just got the FR255 and after finally setting up a training plan for bettering my fitness, I can't set my Edge 830 as PTD. I only get the option to set primary wearable in both the app and web versions of connect. I have the Vivofit HR from 8yrs ago and the FR255 as the only devices I can switch, and even then, it's only as primary wearable. No option anywhere for me for setting a primary training device. Kind of frustrating.
