@roslof Thanks for the suggestion. I removed all but one SoundFont file from the <system> folder and also removed the Gravis Ultrasound folder/files from the <rom> folder as an added check. Unfortunately, no change. Retroarch is still not registering the single remaining .sf2 file.
I don't want to steer you wrong, but this still sounds like the same problem I had. It was scanning other folders (not just the pc folder) and finding .sf2 files. One of which was 512MB and its mere existence prevented the pull-down from displaying properly. Are you certain there isn't a lingering .sf2 hanging out in a scummvm folder or something?
@roslof I do have other .sf2 files spread throughout usr/share/sounds/sf2 and scumm/extras folders. I'll give renaming them a go and see if that does the trick.