I think I figured out what is going on...
I had filter="latest". Evidently, which I did not realize, this only shows the latest 10 items. It won't render more than 10. This needs to be clarified in the documentation.
I had to change it to this:
filter="all" then add sortType="date" so I can display all Web App items in the order of date.
In other words:
{module_webapps id="24183" resultsPerPage="15" render="collection" filter="all" sortType="date" template="/Layouts/Custom/grow-stories.tpl"}