This is awesome! I got it to work in our sandbox. I am running 9.5P10. I ran it against our prod clusters and I get response 0. Is there anything that needs to be done to enable Invoke-NcSystemApi? I didn't do anything special on our sandbox cluster that I can remember. I can't get the script to return anything though except for on the sandbox. And like I said they are all running the same 9.5P10 version of code.
The only reason i can think of why that might be the case is that the account used to connect to your production system doesn't have privileges to run the command. Did you try running it as a user with the admin role to ensure it works then delegate permissions? Another example below of using Invoke-NcSystemApi and formatting output. Might be useful: