This is also a network related issue where you're desynched from the other players and the lobby and will be stuck at the loading screen forever. There is however a trick on discovering this bug instantly. As soon as the race starts to load, press ALT+Z to disable the HUD. You will be where your car was when you entered the lobby for the race. As you will notice you can drive around in free-roam and use powerups if you want to. Now, this is a good way to have somthing to do while waiting for all racers to synch, as soon as all players are synced you will be teleported to the track and you will see textures begin to load. Press ALT+Z again to bring the HUD back up.

When you are driving around in free roam waiting for this, the whole world should be empty. If you see any traffic cars it means you're desynched and have to force quit the game.