Why is merely shrinking doc from "Add Header & Footer" action removing existing header from doc?

Hi,

I have an "Add Header & Footer" step in my Action Wizard step which is meant to ONLY shrink the document (this was my creative solution to add an action to merely shrink documents but not really add a header or footer (which I leave blank with the "Prompt User" box unchecked)). However, depending on the document, it sometimes removes the header even though it is only supposed to shrink the document and leave the header untouched. I am running Adobe Actrobat Pro on Windows. See images below.

Here are my questions:

1. What is it about some documents that makes it such that the action removes their headers but not others? (If I know this info, maybe I can scan for it.)

2. How can I achieve the shrinking of the document without removal of the header? For example, is there:

-a java script code I can use instead of this action?

-another processing step I can apply to the document first before trying to shrink it (with the header blank)?

-a sole action that only shrinks the document that I am just not aware of?