Hi MG,
It sounds like your musical endeavors are really coming along! My apologies for the lag on getting back to you from Christmas as well as here. Suffice it to say things here have been busier than I'd like in some ways.
For the virtual cables, it's important to have them only going one direction from Composer as well as the device they're plugging into. For Notation Composer, your Ports (Setup/MIDI Device configuration/Ports/Select Ports) setup should look similar to the following:
Ports.png
The reason being that if you have both "in" and "out" selected, you can get a feedback loop that can cause your computer to act like it's running on vacuum tubes (or wired to rocks). In other words, it can slow your computer to a painful crawl, so that you can't do anything. By making sure that each connection is only going in one direction, you avoid the possibility of the feedback loop.
After you do this, you'll see that change reflected in your MIDI Device Configuration as having the Maple MIDIs only show for "out" and not "in".
Hopefully that will get you going
If not, just let me know.
ttfn,
Sherry