@Substring : Got It (and I think @IvoLourenco have the same, based on it's evtest).
First of all, I have 2 GPIO (just I was trying to configure first).

You were right, it's a wiring problem (or missing doc for buttons). I had my doubts when I tried to go to Doom. The fire button shoot permanently (as if button stay pushed). I looked again evtest very carefully, and I see that when I press a key, I have the 0 line and then the 1 (So the signal is at 1 and goes to 0 when I press what is the opposite of what should happen - same as @IvoLourenco).

My switches have 1 earth terminal (large side) and 2 contact terminals (small side). I wrongly thought that it was the same thing (no manufacturer's doc) but I just tested with the multimeter and they are 2 inverted contactors (one makes contact when I press, the other makes contact permanently). As a result, the simple act of switching from one terminal to another helped me solve the problem.

In the interface, I think that as soon as you press the button, it's as if you were held down permanently, which of course doesn't work.

Once the wiring was redone, I did a reset of the configuration as you indicated and everything works fine.

Maybe we can add this case in the FAQ and specify that in evtest, we must have:
Press -> 1, release -> 0 and not Press -> 0, release -> 1.

Hope it will help.

@substring : I have exactly the same problem (And I'm french too, don't know if there is some relation). evtest work with each button (and code is the good one for each: Left, North, Right, west, south, east, start and select).

In recalbox menu, I can navigate with joystick without any problem.
When I go to joystick setup, I use any of my button to select player control and it detect GPIO 1. I can set axis without any problem but program stop to detect button after the first is pressed.

For example: If the first button pressed is X, I can't set others, but X works.
If the first button pressed is Y, I can't set others, but Y works.

It's like button detection stop just after a first button is pressed.

I look for a while on internet before finding this thread. May this is the reason of the few number of report of this thread.

If you have any idea