Issue is very simple, when playing splitscreen, 1 keyboard and 3 pads, the 3 pads use default keybinds instead of those in the settings, so you are forced to use r2 for accel and l2 for braking and cant rebind or unbind any other buttons. Interestingly enough, the keyboard does use the custom keybinds from the settings, only the pads dont. This issue occurs with any pad (tried Logitech F310 and 2 ps3 pads) and I recall having the same issue a year ago. Hope it gets fixed because it really hinders the local play.