Backcountry ski used to work fine, and the rest of the time with other activities the HR monitor is fine, but now it's reading way way too low in activities. I think something was broken in the profile in a recent software update. I have a 6 pro, and while I admittedly haven't used BC Ski since last March, it was working fabulously all the last two winters.
For those of you who love replying "why would you use HR during BC ski?" save it. It was working great, it's not working now. It's not the poles, it's the software. It would be great to simply revert whatever changes to backcountry ski were made in recent updates.