Were you wearing a HR monitor and are you registered on zwift power? Some race both these things or they will eliminate you from the results from the start and I the HR requirement isn't always that obvious.

Other than that your numbers don't appear crazy. I would expect at your FTP though to be off the back of a B group race.

EDIT: If you had HR monitor and its was miss-behaving as they often do at the start of a ride it could also cause that issue. If your HR monitor says you are at rest but are pushing over FTP Zwift can think something is fishy.