When you want to change the numbering it requires a new page, but not a blank page. Getting a blank page strictly from inserting a Section break generally requires a "new even page" or "new odd page" break.

You need to view your document in draft view with display of non-printing formatting marks turned on to get an idea of what is happening. Remember, each Section in Word has three headers and three footers, even if they are never displayed they can interact with headers and footers in subsequent Sections.

There is a big difference between Section breaks and page breaks although a Section break can include starting a new page.

Sections / Headers and Footers in Microsoft Word 2007-2013