It appears that I am having the same problem as most. Xbox Fitness was working fine, then all of a sudden after a lengthy warning screen, loads the app and 10 seconds later goes back to the home screen. I was able to get it working again by restoring the xbox one to factory settings, and then reinstalling (after power cycling). It would have been nice to not to have had to do this. I tried many other options before this (as suggested by other threads/posts).
Has Microsoft addressed this as either a development issue, a hardware issue, update related, etc?
Big Poppa Mac