Arthur Keeps Jumping On PC?

I've just bought a gaming PC and am playing Red Dead for the first time on it though I've played the game for years on Xbox.

I connected my Xbox controller to the PC and when riding the horse I noticed my horse would constantly jump when I'm trying to canter/run/sprint, which was odd, so I jumped off the horse and started running as Arthur and Arthur would continue jumping over and over.

I don't remember the A button even being a "jump" button on Xbox, so I plugged in my Xbox and tried it and sure enough the horses didn't jump and neither did Arthur. The A button didn't make either jump, and all the inputs are functioning.

What's wrong with my settings? How do I fix it so it is just the Xbox layout?