If you're using a GameCube Adapter... and Native GameCube Controller Support, unfortunately there's not a good way to fix this. This is a Game Bug that happens even on real console. The developers didn't correctly take into account the GameCube Shell when calibrating controllers for movement.
If you're using an emulated "Standard controller", you can right click each of the joystick movements and increase the range a bit and it should let you go beyond the controller shell a bit which will fix the problem. Doing this too much will cause additional issues with the joystick controls, though.
If you're using an emulated "Standard controller", you can right click each of the joystick movements and increase the range a bit and it should let you go beyond the controller shell a bit which will fix the problem. Doing this too much will cause additional issues with the joystick controls, though.