@zing I'll have a look and see if that's the issue.

Right now I am able to load games with my P2 Joystick being selected as P1 in the configuration menu, and my P1 Joystick as P2. But when I load games with two players it comes up a yellow text at the bottom of the screen saying that GPIO controller 1 is not configured, so I'm guessing that has to be the issue.

@zing thanks for the quick response!
I can't check all the details right now, but I downloaded the latest version from the official website and I'm using a Raspberry Pi 3.
One thing I also didn't mention is that I didn't exactly follow the steps when configuring the pins and what not. Originally I downloaded retropie so I wired my joystick and buttons after another GPIO configuration. For example my P1 Joystick UP is wired to the "A" button. Do you suggest I rewire my GPIO completely since the main reason for games not starting is controller issues?

Hello guys!

I've recently setup my recalbox with 2 GPIO joystick and 3 buttons each (6 in total). I've managed to configure them but I had to skip some buttons like the P1 SELECT and START. I do however have them mapped for P2, and here's where my problem is. I can play games if I'm only playing with my P2 (which has all buttons mapped). Is that where the problem is?
So my question is. Do you need to have every button mapped in order for the games to start?