Here's what happened I was playing a 2 person derby earlier today I was about to win when suddenly the Dream Ghoul who was about 30 seconds behind me(He was horrible about bypassing blockades)suddenly WINS the race and he wasn't even HALF done with his second lapand it says there was a 20 second difference between my time and his time and then my cpu froze and I had to restart TWICE and when I got back into the game I find my point value has gone down form 575 to 555! The ghoul's name started with baby but after the second restart I forgot the name but it burned me up not because I lost the 20 points I can get those back easily but because of the cheat used I have dealt with cheaters on my consoles before and let me tell you it is not fun
The fact that you had to restart to times means it probably wasn't the other racers fault. I think you have a bug of some sort. Try doing a bug scan. Maybe the reason why the game forgot your progress was because of a known game bug. Lately people have been loosing progress ever since the pet upgrade. although ussually with items it could also be pet exp. Also the race thing was probably connected to one of the other things some how.
While the whole restart thing i am at a loss at, i would like to point out that the ghoul thing could have something to do with your connection. that somewhat happened to me once. i was almost to the finish line in a close game when then i was about 5 feet back from the finish line and i think it was a magma spider that won