Query rule results block with more than 10 items

Following this tutorial to have the faceted navigation on my site with two content search web parts on the page.

I've got it working. I have one webpart called individual items that searches the individual results source and that fires off a query rule which searches the grouped items result source and provides those in a result block called grouped items.

The problem is that the results block in the query rule is limited to 10 results. Most of the time this works, but occasionally I know that there are more than 10 grouped items.

Does anybody know a way to have more than 10 results passed from a query rule?