iOS 18 bug? Apple Fitness+ on Apple TV not working

My experience was very similar to yours. Having spent some time with Apple Support over the phone, I wanted to let you know of my experience thus far in case it helps.

When I first tried Fitness+ after the iOS 18 (or equivalent) update, my name wouldn't even show up on the list of available users (other family members who didn't update to iOS 18 did show). After switching the Apple TV, iPhone, and Watch off and on again, I still didn't show up in the list of potential users but I could choose the "Other" option and join in as a guest. That didn't get me too far, though, because once I picked an exercise and started it, the Apple TV would hang there while a "Looking for your watch" message was displayed.

At that point, I spoke with Apple Support for the first time.

Their recommendation was to unpair the watch from my phone and then re-pair them. After doing so, my name appeared in the list of Fitness+ users, but if I clicked my name it asked me to verify myself on my iPhone (the option for doing so on my watch was not available). It works, but hey, I want to see my stats on the screen!

I was, however, able to use the "Other" option again and connect my watch to the Apple TV as a guest. It's awkward, it takes extra time, but it worked. And this time around, I could actually run the exercises.

Apple Support is still looking at my case, given things are less than optimal still. By now the case has been escalated up the engineering chain. Regardless, the point of my story thus far is that unpairing/pairing the watch could help, if only to some extent.

Just a short follow up on my previous entry:

Some 3-4 days after I unpaired/paired my Apple Watch, I woke up with a message on my iPhone informing me that a new device, a watch, has been registered under my account for iMessage & FaceTime.

Since then, my Apple TV has been recognising my watch, and it's been all smooth sailing (or smooth exercising). Just don't ask me why it took 3-4 days...