When I built mine, I put the return pump in the chamber and ran it emptying into the intake section to get an idea of how flow would work.
From what I can see in your pics, it appears in the lower water level one, you have weirs on every baffle, those would set the water level points there.
Those weirs all appear to be at that hieght, and without enough flow going to the point where those lower weirs can't keep up, that will be the highest point in the chambers if what I am seeing is correct and the water level is in fact all at the weirs accross the entire sump in the pic with lower water level. Also with that design, at rest, its going to level unless severely low