I’ve been a flying bike twice. Happened when I was with a pace bot and paused or exited (can’t remember exactly). When I restarted it was like Zwift forgot where I was and drifted me to the nearest road. When I reached a road it snapped back to normal. In Strava the tracking shows a dead straight line between two parts of Watopia
edit: just remembered more about the last one. The iPad got to 10% battery and the warning crashed Zwift. When I restarted and Zwift asked if I wanted to continue, I was placed flying in mid-air
This can happen when a rider LATE-joins a group-ride, for example, and you will see the message “looking for riders”… as Zwift transports the late-comer to the rest of the group. I think this can happen, too, when joining the Pace Partners… The other instances, mentioned below, not involving flying bikes, but rather steering-enabled setups who delight in defying the “physics” of staying on the road! Yesterday, coming around the Volcano into downtown, I saw multiple Zwifters cutting the corner of a roadway, and driving right through the guard-rails. But that’s nothing! There was a floating bear, too! LOL.
Stray and flying bikes exist outside the parameters you listed, or/and long before the dependent “feature” were added. Multiple stray riders sometimes appear to be taking the same path, as if there was actually a road there… (which resulted in flying bikes in NY…)