@johnelemans I have not but the Nest does provide power readings and they are consistently above 32 volts. I'm going to assume if that is indeed the case that the common wire is properly grounded.

Thanks @Harper for that explanation. I am not sure why Nest senior support was so emphatic that the common wire was not "grounded" in such case. I am going to have a technician look for any other possible shorts, loose wire nuts etc that might be causing this intermittent off/on switching of the compressor.