Waht has been described earlier in this forum happened to me last night. I was taking part in Challenge #68 in the J/70 and was doing really well - much better than I had ever acheived before.
The first thing I noticed was that I wasn't getting any cans at the end of a race. Then I noticed that I wasn't getting any races recorded. As a consequence, I know I lost a 2nd and 3rd place. That was a real disappointment as it would have pulled my challenge ranking up quite a lot. I submitted maybe about 10 bug reports.
I have lost getting cans before now when my iPad has either frozen or has stopped responding when the can displays.
I agree that it is a big pity that the game developers do not seem to be willing to respond to issues such as the above - it really does diminish one's enjoyment of the game.