When I purchased my F7X, doing an indoor walk (which is a walk activity with all GPS turned off) was quite accurate on distance. I've noticed that with the latest software versions this is no longer the case (it overestimates distance by 10-20%). I have tried setting a custom stride length in settings but this has had no impact at all. Has anyone else experienced this issue and found a solution or know why custom stride lengths are not being picked up on a walking activity?