This concerns Smooth Slider version 2.5.
My blog's "Reading settings," "Front page displays" are set to a static page.
The Smooth Slider update isn't respecting the "Maximum Height of the Image" setting (at the "Slides Panel," "Thumbnail Image") on that static front page. It is rendering full-size images and isn't showing the Navigation Buttons either on account of it.
Otherwise, the thumbnail size seems to be working on the site.
Therefore, I've rolled back to Smooth Slider version 2.4, which is working fine.