Another bug to add to the list since the new update on the Atom - it might not be related, but considering it has happened to me in BOTH the races I have done since the steering wheel icon appeared, I’m thinking there’s a good chance it’s the cause. Rather than no-one else appearing in the world as reported above, I COULD see everybody else, but they could not see ME.
All my team mates on Discord confirmed my avatar could not be seen on the course even when I was riding alongside them and I didn’t appear on the Riders Nearby list either. But not only could I see them, I could even draft off them and I was apparently appearing in the sprint / KOM leaderboards for everybody. Also my race rank was always showing on my screen as last (e.g. 66th out of 66), even though riders were behind me. At the end of both events I checked ZwiftPower and I was in the results at the correct position for both rides.