iBuffalo USB Gamepad: Works with EmulationStation Menus, Doesn't Work with NES Emulators

[johnc]

Lots of headbanging, searching, trying things. Hoping someone here can help me out.

The problem
I have the iBuffalo Classic USB Gamepad. After configuring through EmulationStation, the controller works in EmulationStation menus and in some emulators but not all emulators. For example, it works in Super Nintendo, but not in Nintendo/NES games. Also notable, the controller registers as "configured" in yellow at the bottom of the screen when games start. Confirmed that the problem is all buttons in NES, not just select/start.

My Setup
Built a Picade cabinet, no customizations.

Pi Model or other hardware: 3B

Power Supply used: 5.25V 2.4A

RetroPie Version Used: 4.3.5

Built From:
Official Image Retropie Image: https://github.com/RetroPie/RetroPie-Setup/releases/download/4.3/retropie-4.3-rpi2_rpi3.img.gz

USB Devices connected:

• Picade Arduino board for arcade buttons
• USB Keyboard
• iBuffalo USB Gamepad
• LCD screen powered by USB

Controller used:

• The Picade joystick/buttons (works)
• iBuffalo controller (the problem)

Error messages received: None

Log found in /dev/shm/runcommand.log (if relevant): Not relevant

Guide used: Various

Emulators: Tested with all NES emulators: lr-fceumm, lr-nestopia, lr-quicknes

Attachment of config files: Unsure what's needed here. Tested using a custom config for nes, but abandoned idea/deleted the file.