With start button centred, the switch 'Do not offset the menu horizontally to ensure it lines up with the start menu' is operating in reverse of what you would expect from the wording.
When switched to 'ON' the menu is offset, when switched to 'OFF' the menu is lined up with the start button.
Setting has no effect at all if start is left aligned.
I think it sounds like it is working correctly?
You would enable that option if you did not want Start11 to shift the menu to always be above the start button. By default Start11 will ensure that there is overlap between the menu and the start button when centred, but if you enable that option it will not and instead will work like Windows 11 does and forces the menu centred regardless of where the start button is (assuming you have centred mode enabled)
We usually offset because it is a poor user experience to have a button you click to open a menu and then have to move your mouse a distance to get to the menu that was shown. This is particularly bad if your taskbar is full of buttons.
