Cant make a group to align with another group

Hello. Can someone help ? When placing rectangle with thickness as a group) on top of a vetical rectangle which is a separate group, it does not align correctly. Il simply refuses to align. It jumps to a position a few centimer before or after. It looks like there is a sort of snap to grid which is on but not functioning correctly.
How can I solve this problem ?

Same question about having edges not displayed.
Also turn off length snapping. It doesn’t help in modeling accurately.