When using the heat option it resets my rep level as well. I set it to 5 so i could get to heat level five easily and then suddenly my rep level was at 5.
i had to set heat to 50 to get my heat level back and it gave me over 4 billion rep for it.
Hit the same issue, but I noticed that the next level was still shown up in the top right. After I ended a night, I still managed to level up to my next intended rep level (31 in my case). I had to do another night and end it after one race for it to show my rep level as 31.