" but the difference between rotating it once and not rotating it is very marginal" Marginal though it may be, it's a difference, and to a computer that is all that is needed. When a Computer is presented with a choice where to connect a belt in a system of two pole identically phased (both are facing each other directly, and no difference exists between the angle from one face to the right and the same face to the left) then the computer will make a choice based on some kind of rules in the code. Turning one pole ever so slightly now presents an angle that is smaller than the other, no matter how much smaller, smaller still, so that gets chosen.
More to the point though... vertical belts are coming, so these structures are irrelevant now.