@drjb,
Sense monitor powers itself off of one leg, but samples both legs. That’s why you need to hook it to a (hopefully) dedicated 240V breaker. You can see different 1/2 second RMS voltages and power/current on each leg in the monitor Signals section. My voltages are balanced right now, but they often vary by a volt or two.
I’m also going to point out that you really don’t want a live trace of AC current and and voltages following the 60Hz cycle. You want an RMS reading like Sense presents in the Power Meter. If you do want to see readings for the leg splits, look at the Signals section and just divide the RMS power readings by the RMS voltage to get the current. The current hack is to use the informal API, like this gent did:
And if you want to do real bandwidth monitoring, the easiest way is probably to replace all your networking gear with Ubiquiti gear. That’s my plan once they update their UniFi In-Wall HD Access Points handle WiFi 6.