toscho…you were partly correct but helped immensely. Turns out the issue seems to lie within the theme’s attempt at calling up the scripts. My WP install is in a subfolder (/wp/) and it was looking for the wp-include scripts in the root folder. All other aspects of the site work fine, so I assume this is just an error somewhere in the theme’s code. I “fixed” the problem by copying the /wp-include/js folder into the root of the site and low and behold it’s functioning properly now. This is definitely a band-aid fix though as I’m using duplicate script locations, but since it appears to only affect this one area of the admin panel it shouldn’t cause any issues.
I’ve dug around the theme’s relevant PHP files and can’t find where the problem lies. Should I look into this further or accept my workaround as a fix? Either way, I appreciate the input as it led me in the right direction.