This might be a further clue. Check out this url on my test site:
https://wp1.smallworks.ca/blog/classyfrieds/
Scroll down the page and you will see all the test listings in single layout with that same large white space above.
I did not create a page called classyfrieds. I assume classyfrieds did this on its own as the plug-in is sort of a subset of wp blog categories (?).
However, the other pages that classyfrieds created on its own–listings and add_a_listing–appear without including this /classyfrieds/ page or category or whatever in the url.
Mean anything?