@hhcasey Which USB port is this plugged into?

The ports matter, they are numbered. Make sure it's in the lowest, see if that helps. It helped with my Pi3 and another controller interface I had plugged in. If i put it in any other USB port than USB0, it would screw everything up.

I don't know how the Pi4 ports are numbered, because they have 2.0 and 3.0, but make sure your controller is in the lowest of all ports.

Maybe see if that helps. Other than that, I'm at a loss.

But yes, MAME for Linux/Retroarch is not the same as for Windows. Maybe in the conversion there is something that is causing an issue.

Try all the versions as well, including the FreeBurn emulators as well. See if any of them pick-up your controller.