RetroPie iBuffalo usb controller can't hold down y button

I recently got the iBuffalo Usb Snes controller for my retropie build and booted up Super Mario World. Immediately I realized that when I would hold the y button down (to run and pick up and hold shells, etc) it wouldn't let me press any other buttons. If I turn on the turbo for the y button then it will run quicker, but never to the full extent required to jump higher or to hold shells. It seems that the controller only does a single fire type action for each button press, unless turbo is on which just repeatedly fires the action instead of doing what the original Snes would do.

I'm wondering if there is a setting that I can change that will provide me with the desired functionality using this controller or if I should return it and get one that will work (bonus points if you know of one that does work properly!).

Thanks!