Official statement from Peloton:
“Apple GymKit is designed to work with equipment-based cardio workouts. However, Peloton recently implemented GymKit with Bike Bootcamp, a multi-disciplinary class type that combines strength and cardio, which the feature does not support. Members can still use GymKit to sync their cycling-only workouts to their Apple Watch from the Bike+.”
One of the selling points of upgrading to the newer, upgraded, and more expensive Peloton Bike+ was the inclusion of the Apple Gym Kit, an Apple platform that makes it very easy to pair the bike with your Apple Watch to see your heart rate and have your workouts directly imported into Apple Fitness and Apple Health.