Hard reset your Xbox One by holding on the power button while it’s on for about 10 seconds. Once it’s turned off, unplug it from the mains outlet and leave it unplugged for a minute or two. Then plug it back in and start Forza up again and see if it’s still doing it.
The game seems to introduce new bugs with content updates (I’m been rather vocal about those), but this one your describing, not at all. Can you upload a video please?
The Replay feature is the main reason I bought Forza 6. But I do not see what “sideway jerk” you are talking about. A video of your example would be great.
I’m getting the same problem. Replay is constantly jerking and yes for me also one of my favorite aspects of forza. Wonder if any of the Turn 10 developers read these forims.