Ive made an odd observation yesterday. I was 5th on the daily leaderboard with Jamma in 4th. When I raced it only matched me with 3 ghosts instead of 4, with the missing ghost beings Jammas. I beat his score to go in 4th but still raced with his ghost missing.
Now that the leaderboard has filled out Im back to racing 4 ghosts, all randoms of course. It was a shame that these random friends filled the leaderboard as I dont get to race against my actual invited friends. I hope the missing ghost is just a one off and not a sign of a deeper problem with racing the people you actually want to race.