Bug: Player character can't perform attacks if pressing against a wall (pressing a directional key towards a wall while touching it). Attacks in contact with the wall are possible, but keeping any button pressed during it makes any attack a failure.
Possible cause: The vertical attacks trigger when the attack button is pressed while a directional attack is triggered, and the forward attack triggers when the player speed is 0 (they're still). If the player is in collision with a wall, their speed is 0 - the forward attack triggers. However, a directional input is being pressed, and a conflict happens.
Possible fix: The exact state machine result of this situation is not yet determined, so this is preliminary. Instead of using inputs for the vertical attacks, use player speed as well. "If player speed = upwards movement, up attack; if player speed = down movement, down attack". This may have other consequences, however.