I am seeing behavior that looks like a problem with the layout settings on the header positions. No matter what I publish to any header position, or how I set it, including forcing, the only positions that seem to be working are A and B and they split the page 50/50.
I tested the same config I am trying to get on the header in the top positions and they work fine. The same config in the header position aligns position B's left most edge dead center in the page no matter what I do.