Hi, @hobs. I enjoyed reading your post—for the information and thought you gave—but I am sorry for the trouble you may be having in your house.
So, the image you posted, which I included below, looks very much like an issue we sometimes have: power quality in Sense records erratically and then may stop recording entirely. A “reboot” should do nothing to influence if you have bad power quality in your home, so for anything before that date—especially with the big spikes—I would be skeptical of any data you see.
I would mention, though, for users who see issues like this, "Did you find your lights flickering? Did you find your other devices failing to run well or acting erratic… and as you posted here, it appears you did as well. So you may be having both of these issues.
The first step, as you did, was to reset your Sense monitor. This is actually one of the issues we discussed in the blog post @kevin1 just wrote about the signals page. If you checked before the reset, you might have seen a deviance from 60 Hz in the frequency section—also, maybe not.
If you have not, I advise you to file a support ticket so we can look into how to help you. If you need my help, feel free to send me a private message.
Going from a 3-phase setup to a single phase - as @kevin1 said, is important to mention as Sense is generally equipped to handle a split-phase home rather than either of the other configurations mentioned, so there may need to be a few things that we would need to check on our end specifically.