useRootPaddingAwareAlignments and top and bottom padding

I’m developing a hybrid theme and the site has a sticky header. I’ve set styles.spacing.padding top to be the height of my site header so that content in the first block is pushed down below it. I also have some inline padding.

"styles": {
		"spacing": {
			"padding": {
				"top": "calc(var(--header-height) + 2rem)",
				"bottom": "2rem",
				"left": "2rem",
				"right": "2rem"
			}
		}
	}

I have useRootPaddingAwareAlignments turned on so that inline padding is applied at block level and full-width elements span the viewport. I was hoping that this setting would also affect vertical padding so that the first block in a page would get its own top padding, plus the root top padding. This would allow the block’s background image/colour to appear behind the floating site header. However, that doesn’t seem to be the case.

Is there something else I need to do to get this working, or does WordPress simply not handle vertical padding in this way?