I also had this shuddering problem on my 2017 8-Speed, as well as while driving at low highway speeds (50mph) in high gear, if you watch the tach, you will see it occasionally drop slightly, then back to normal 3/4 of a second later, indicating the torque converter 'slipping'. I took it in to the dealer where they performed the TSB of the fluid change - I was extremely skeptical, but that fluid change (to a different type fluid) completely solved all the problems, and they haven't returned several years later. Good luck.