Since you took her to the chiropractor, I don’t think it has to do with her muscles or anything like that. She is probably feeling good because she doesn’t have anything out.
So, I would suggest to make her go to the left anyways. I have had horses throw a fit just because they did not want to go that way. I drove them forward until they went the direction I wanted. After I convinced the horse that they had to go that way, they had a better attitude and that specific problem never happened again. I hope this helps you with you question!