I don't know much about bits, or barrel racing, so feel free to disregard my answer
But, it looks like the mouthpeice of the bit you are using is fairly strong, and if it is not working, I personally would go back to basics for awhile. Meaning, work through the barrel pattern at a jog, and switch directions so your horse is not anticipating that second barrel. Also, lots of small circles,serpentines, transitions between gaits, etc., just to re-establish to the horse that your aids are to be followed. Good luck!