On the 2019-in-1 board, the 5th and 6th player buttons aren't ran from the JAMMA Harness. There is another cable which plugs into the top of the JAMMA board which you need to connect the player 1 and 2 5th and 6th player button. The cable is the one with the white plug with 5 wires connected to it, the other end will be cut wires.

Wire Colours

black = GND

red = 2P Button 6

white = 1P Button 6

yellow = 2P Button 5

blue = 1P Button 5