UPDATE: This may actually be a coincidence as speaking with Servertech yielded the thought that it may have been the reboot more than the SSH that got it working. I cannot say for certain that I rebooted between having the CDU monitor the UPS, and enabling SSH. So, YMMV.
Just figured out that to get UPS monitoring to work on the Servertech CDUs, SSH has to be enabled on the CDU. Until that time, I saw N/A for both voltage and status before that, then once I enabled SSH and rebooted the CDU, it started working perfectly.
Not sure if I could turn it back off at this point or not, but since I have a firewall protecting the CDU, I’m not too worried about having SSH on.