I added a row at the top of the report and it works fine but the report print blank pages in between. So if the report is 3 pages it will print 6 pages with a blank page in between.
That sounds like a column got slightly wider, causing it to spill onto extra pages.
Check the width of all controls, and ensure they are less than your page width Letter or A4. Don’t forget the defined margins too, they eat into the available page real estate.