Hi, I just wanted to follow up with my findings. It seems since updating to later versions of OSX I've found the USB connection with the MOXF to be far more temperamental.

To get it to work I perform the following:

1) I restart my computer with the MOXF off and the connecting USB cable directly plugged into both the MOXF and the Mac
2) I THEN start the MOXF

This seems to yield consistently working results. Without a restart of the computer, I rarely get the MOXF to work properly in conjunction with the computer.

It might be that the Yamaha Steinberg USB Driver needs to be updated by Yamaha. This worked far better on earlier versions of MacOS.

Anyway, away we go. Thanks to Big Mister for his ever kind and perservering assistance.