Additionally, it was working with a beta version of a Yamaha Steinberg USB Control Panel (4.0.3b). When it stopped working, I reverted back to the official release of the Yamaha Steinberg USB Control Panel. (3.1.4) I've deleted and installed both versions and neither seems to work now.

It's a Yamaha 01V96i digital mixing console with a USB computer connection for 16 audio inputs and 16 outputs. It's not recognized in the audio window of Audio/Midi Setup but is recognized in the Midi window. The midi implementation seems to work fine in terms of controlling faders on the mixing console from the computer and the from the moving faders on the console corresponding to computer screen.