I did swap the cable, though I guess it is conceivable both are malfunctioning. Also, I’ve been using the same cable to program and query two different Arduino devices without issue so I’m pretty sure it is functioning. I just got my first response back from support. The first line was “The RSP does not use serial ports it uses a high speed USB 2.0 port.” Guess USB means something different than universal SERIAL bus in the UK. Hoping for the best.
Thanks for your response, Rick.