I finally found the issue in installing on my iMac using Mojave. Upon original installation, I did not enable the microphone. Subsequent de-installs and reinstalls left me with the error that is was running but not accessible.
Through trial and error, I went into
Systems Preferences -> Security and Privacy -> General
At the bottom of the screen is a line that says “Some system software was blocked from loading”. I then clicked the Allow button and noticed that DPS was being blocked. Checked the empty box, rebooted, then reinstalled DPS. It gave me the microphone access dialog box, which I enabled and it now works!
I apologize if this had been ID’d before, if so, somehow I missed it..