IMO, over ~54.7v or so, is starting to rise into the knees and around ~ +95% capacity. If the axe is like the bms in the basic eg4, it will push the inverter to charge close to 58v, which is way up into the knees. Not a lot of power up there. Not that good on the battery either. Why the inverter is reading different voltages at the same %soc, don't know. Maybe flaky data connection? Have you confirmed the voltage reading with a multimeter?
In post #10, you are importing power from the grid, or in this case, a generator.
If it were mine, it would be going back to SigSolar.