tl;dr: It now works. The installers added a remote Neurio transmitter in the main panel that was redundant double-counting the total energy consumed. Neurio removed.
Well, Tesla was here today to meet with the town inspector, and arrived about 90 minutes before the inspector did.
I showed him the erratic power flow behavior I posted about above, and he agreed that was very strange. He got Tesla tech support on the line, and to make a really long story short, it took three of us and about two hours to finally get it resolved.
At first the tech support guy said there's a new (and still unfixed) bug in the latest TEG firmware causing the double readings from the CTs. But as we all went through the design and layout, they realized that the Neurio remote sensors on the main 200A service line weren't actually necessary. Between the remote CTs and the CTs inside the gateway (they're called the "X" and "Y" sensors), it was double/over-counting the total home power draw. The remote Neurio CTs measured everything, and the GW CTs measuring the backup load panel so the total power draw was being over-measured.
Once we removed the remote CTs from the main service lines, instantly the readings became non-erratic and the system started to function normally and solar was then providing 100% of the house draw (more on this later).
So then the Tesla guy removed the Neurio from the non-backup-loads panel, and suddenly the solar turned completely off. We powered up the Neurio again (still with the CTs removed) and the solar started producing again. So the GW configuration was still looking for the remote Neurio before engaging the inverter. So we went into the configuration wizard on the Tesla guy's phone and removed the remote sensor from the config.
Then we waited and waited and waited, but the solar never kicked on again. We put the system into off-grid mode to draw down the PWs to 98%, but even still, the solar would not kick on. So we called tech support again, and while they were looking into it, the inverter kicked on. Turns out (and most of you know this already), when the PWs are full,
and I don't have PTO/export yet, the inverter shuts down the solar production. Anyway, I guess one of the two PWs dropped below some threashold and the inverter was able to kick on and supply the house with power again.
The only downside to this entire experience is that now the Tesla app and power flows and the grafana web monitoring tools do not include my non-backup-loads panel. Everything now only reports the backup-loads panel as-if that was the 'entire house'. I can live with that, I suppose. My SENSE meter can measure the whole-house loads, except it doesn't handle net metering at all.
They may have misconfigured the setup of the CTs so that it is using the sum of the remote CT they added to your panel and the CT inside the GW2.
Pretty darn close! They were not misconfigured, they were totally not necessary!