Well, the site contains sensitive information so I was reluctant to link to it. So I was trying to set up a scrubbed version of one of the posts giving me trouble and found a weird thing. When I access the post in the same instance of the browser I use to create posts and maintain the site, I get the weird spacing. But when I access the same post from a different instance of the browser, the spacing is not problematic. So I have no idea what might be going on that is browser dependent the way this problem seems.
However, any guidance on change the default caption font would be most welcome.