My problem was that the file nbr-product-page.tpl wasn't being called by my theme. More specifically, it was being called but someone had commented it out because they didn't want the select field where visitors choose how many products per page they want to show up. So instead of hiding it with CSS they commented out the include for that file.
I'm using a custom theme and am new to Prestashop myself so can't give much better answer or more details than that. Basically, at some point in your product display file you need the following:
{include file="$tpl_dir./nbr-product-page.tpl"}
That was my experience at least. If you do a find-replace for nbr-product-page.tpl that should get you going in the right direction.