Controller acts stuck – Kodi on RetroPie

I am running Kodi on a RetroPie v4.0.2 (I think) and am trying to use my xbox controller to navigate. When Kodi boots up, the menu just begins scrolling, as though some control stick was stuck. If I press up or right on the right analog stick, the scrolling stops, but I can’t do anything from there. When I disconnect the controller, everything is fine. I use the iOS app to navigate, but really want to be able to use the controller as well. What am I doing wrong!