So he had a very light injury that didn't require a card, which makes sense, because you were able to bring him back in, during the same game. This happens sometimes.
In general, injuries are randomized and the likelihood of them increases when a player is played heavy minutes even during one game. So it's inevitable that some people will have their Kobe injured during this 2nd challenge.
Super annoying to play such a long challenge and have the time wasted, even though you make enough MT to not lose MT on Contracts.