I can't do a Left Ground Grab during the mission Transition 101

Hi! Do you by any chance have a keyboard with magnetic or hall effect switches, like a Razer or Keychron? If you do, try unplugging it to see if that helps. Also applies to any non-standard peripheral like a flight stick or racing wheel.

If you're using Steam Input, it sometimes rebinds the triggers to be the bumpers, and just unbinds the triggers entirely. Try checking your controller bindings!