I was able to register for CSR about 10-15 minutes before it started, as was Kamikaze Miao. Then the mission disappeared and there were no notifications and no tracking of the race.

Myself and Kamikaze Miao still ran the race, I came in 1st and he was 2nd, but as far as the game is concerned it appears that it was broken.

Thanks, this was apparently a longstanding bug. We're working to now make the whole mechanism more robust.