Spent hours trying to get this right, finally managed it. Noticed a lot of online forums with people in a rage but I might be able to help.

three things:
1. Crash! Deny yourself a revolution because they often cancel out abilities.
2. Stay wide. There's a couple of horses in this challenge that will slow down seemingly on purpose to ruin it for you, so stay wide on the final bend and stick to 14th of 15th position.
3. Use normal whip once!! No windmill and dont show whip beforehand. Get the horse on the straight, in 13th-15th and hit it once. It should trigger last to first, then whip her again to get your go baby go on.

Hope this helps somebody out there because mostly people seem to think it's a glitch.