When you start your car, instead of a normally quiet start, does the engine start up right away? When that happens to me on a gen 1 that means it's really cold outside and you left the car unplugged and didn't precondition the battery. In that situation, cycling through the drive modes will not allow me to select some of the modes, so I imagine regen is also disabled. Basically ice is supplying all the traction electricity until the battery's heaters can warm the batteries sufficiently. Think of it as battery preservation. You don't want to be charging or discharging a frozen battery and destroying its longevity.