I am using a Xbox controller too. I will try to fix it
Viewing post in Suggestion or Bugreport comments
If the problem remains then I think it has to do something with the called "input dead zone". Quick explanation.. Some Controllers have an idle input of up to 0.3 which causes the player to move without any "known" input.. However that is a bit harder to fix because I am not able to let the users individually customize this dead zone.