Your whole approach makes no sense. If you want exact, non-antialiased shapes don't use scaling! Resize the shape path rectangle to exact dimensions and place it at full pixel value increments. 55% is not an even divider value, anyway. You have to understand the math here. Also of course none of this really matters if you zoom in 1600%. The only thing that is relevant in AE is how stuff looks at 100% because only that is waht is going to end up in your final video. You have several bad workflows here. That might also explain any discrepancies with the grid, as AE simply has limitations in how precisely those overlays for grids and guides work, which in itself of course also doesn't make a lot of sense if you don't actually show the rulers to verify grid orientation and guide placement.