Whenever the load on the two phases differ the grid CT would read that the power on one phase goes positive and the other goes negative for ~half the power of whatever I turned on. So in the screenshot case, I turn on a 1400w space heater, phase A would read -700w and phase B +700w. It seems that the inverter is feeding the 1400w across the two live wires instead of phase A and neutral, so half of that power is flowing "backwards" from phase B to phase A.
I haven't seen this inflate my utility meter reading but I'm not sure if that will still be the case once they swap it to a two-way meter. The immediate issue this causes though is that the inverter reported readings for feed-in & purchased energy are very inflated. My system is configured for zero-export and in the screenshot you can already see that it has double counted 24 kWh of feed-in because of this issue. This messes up all the self-consumption and self-sufficiency stats.