Creating a Patterned Layer... with a gap

I know how to create a patterned layer from a selection, however, I find that if I have any empty space that I WANT, it is not kept when I create the Patterned layer from Selection.

Here is an example. I have created this seamless section that I want as a repeated pattern:

Despite having a wide selection above and below that section, when creating the Patterned layer FROM SELECTION, it ignores that space:

The only gap, in this example, comes from the faint shadow.

Is there a way to actually respect the intentional space when creating the Patterned Layer from Selection?

Quote from Oufti

Have you tried to add a line with no fill no stroke at the top and bottom (on the dashed line) of your pattern?

I guess that is an idea; a line that is obvious enough and separate enough to be removed. That is a workaround.

I am just puzzled that it is called "Patterned Layers from Selection" yet, it does not respect the selection.