Tried this exactly as you wrote but with the current stable build on a Pi3b. What happens is this: https://i.imgur.com/KJeZjIa.jpg

Here is my config:

## GPIO Controllers ## enable controllers on GPIO with mk_arcarde_joystick_rpi (0,1) controllers.gpio.enabled=1 ## mk_gpio arguments, map=1 for one controller, map=1,2 for 2 (map=1,map=1,2) #controllers.gpio.args=map=1,2 controllers.gpio.args=map=5 gpio=5,4,14,22,13,18,21,16,6,20,26,12,-1