Actually there are 2 issues, which might be connected together or maybe they are separate?
Player 1 start button only registers upon release, when pressing it, nothing happens, while releasing it triggers.
This is really difficult for me as I use 'hold start' to go to the test menu.
If I connect a keyboard or USB arcade stick, start buttons works like it should.
Apparently this is standard behavior for the JVS-PAC:
On here I found that P1 start is issued after release, so perfectly matches my 'problem'.
Can this function be disabled somehow?
If P2 start is hold down and P1 start is pressed, the P2 start freezes until I unplug the USB from the JVS-PAC to the PC
The rest of my setup looks like this:
Namco Cyberlead cab with standard Namco I/O
PC installed with Lakka, so no Windows involved.
When I test the P1 start button with arcade PCB's everything is OK, so I'm only having the issue with the JVS-PAS connected.