Mine still works. For what it’s worth, I put basically no stock in this calculation, though. I wear my Apple Watch 24/7, including for running and racing. This weekend I ran 68:39 for the half-marathon - not my PR, but not too shabby! Apple says my VO2 max is 60 (which it has not improved this training cycle, despite significantly upping mileage and running workouts). Garmin handles this much better, in my book.