I had set up a different first page as you noticed. I did a print preview and I exported to PDF and the blank page showed, So it was there as you say. Any reason why it does that? Wouldn't it be more intuitive to be able to see the blank page? Sometimes I also want to add something to that page.

If you want to add something to that page, type at the end of the previous page until it wraps (before the section break), or put a manual page break before the section break, and type away to your heart's content. Place-holder pages like that in books are traditionally completely blank.

Solved. Thanks.