I don't know what caused this, but I have a literally unbreakable barricade in the Road Trippin race and it stops you from getting gold. You can smash into the river out on the left side in order to get around it, but getting gold time while doing this is literally impossible (without maybe a literal speedrunner running it).
If the devs added literally two seconds to their races gold timers, then you could go around this and it wouldn't be an issue, but that just my inner "time trial in a non racing game" hatred peeking through
I have verified files AND redownloaded the game and rolled my save back (to the last main story save which was 5 painstaking races ago) and nothing has fixed it