Managed to get some time to play with the ADE7763 over the weekend. During testing of the SPI interface I found numerous problems with timing that I corrected. I am now fairly confident that the underlying digital interface to the chip is correct.
My next activity was to provide a zero volt signal to the V and I channels and insure that the IRMS and VRMS registers would read close to zero. They did not. I even enabled the DISCH1 and DISCH2 bits in the mode register to internally short the ADC inputs. But I still found that the values were not close to zero. I then noticed that If rather than shorting the inputs to ground if I connected them to a wiper on a 100K pot across Vcc that the IRMS and VRMS values would change. This counters my concept of a differential amplifier/DAC input. I sent in a request to Analog and hope to hear back soon.