Well, some good news.
I have connected the C phase blue wire to one of the two phases on my 120/240V system.
CT around one of the two 240VAC wires that connect my Enphase battery system (AC in/out) connected to Phase C input.
Went thru the Solar/Wifi calibratio:
https://help.emporiaenergy.com/hc/en-us/articles/9557604644631-Reset-WiFi-Solar-Setup
Saw no change when I finished, but wait.
The next day there were plus/minus signs on the Channel C data in the .csv files!
SUCCESS. Not sure why it’s such a secret but I got it to work!