Thanks for the suggestions! I set the MSC-400 to ID 10 and it now displays all available ports in the MX-980 RF window. As far as I'm concerned this isn't simply a work-around, it's a necessity to properly set up the MSC-400 because it's also the only way to see the port's labels from the RF assignment window.

FYI (for anyone else) it's RF ID 10 in HEX (0x10, so don't set it to 0x0A) :)

So does anyone know what "Blaster 1" is?

I can get by without addressing those ports specifically from the MX-980, but I might as well have the ability just in case I do need it. I have multiple sets of LED lighting controllers that all respond to any and all NEC codes, regardless of device ID, so they have to be routed individually.

I'm still disappointed the RF performance is so slow/laggy and that the reception isn't absolutely 100% even with two receivers in a 15 x 13 foot room. BUT... That could be just due to the issue of residual RF I mentioned in my first post and more common with the second or subsequent commands sent.

However, with only a single receiver, placed up near the ceiling on one end of the room, the reception was poor even sending a single command, depending on the position/angle of the MX-980. Keeping the remote oriented vertically worked well, but IMO, that's kind of a PITA.