Emulator, Controller, and Making Combos

[GryphusOne]

Hi there! New here, first time using PPSSPP, and just bought a Logitech f710 controller. I'm playing God Eater Burst, finished it already on my PSP, trying out PSP emulators and controller. I configured the controls, put in my data, everything is fine. Except that I can't do combos. For example, ⬛ is light attack, and ? is heavy attack. ⬛ + ⬛ + ? is a combo, but ? isn't following up, resulting in me just being able to either spam a couple of light hits or heavy hits. Is this on the controller or the emulator's side? Thanks!