There has been a change in the way Word honours the Paragraph Space Before setting on paragraphs appearing at the top of the page.

Prior to Word 2013, if the paragraph had both Space Before and Page Break before, it would push the paragraph down the page. If if didn't have Page Break before but did have Space Before then it would collapse the Space Before (which made sense since that paragraph just happened to fall on a new page rather than being forced there by a setting).

The new behaviour is actually part of the document compatibility format so you can see the changed behaviour by changing compatibility mode in a document.
If you run these commands one at a time you can see when the different formatting behaviour occurred.
ActiveDocument.SetCompatibilityMode (wdWord2016)
ActiveDocument.SetCompatibilityMode (wdWord2013)
ActiveDocument.SetCompatibilityMode (wdWord2010)
ActiveDocument.SetCompatibilityMode (wdWord2007)

So the 'solution' for your document is to change the document compatibility mode.

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Andrew Lockton
Chrysalis Design, Melbourne Australia