Thread:Extension talk:SectionHide/Having trouble getting this extension to work

I've followed the instructions exactly to get this extension working, and while I do see the "hide" links next to each section on my pages, clicking on them doesn't seem to do anything.

I'm running MW 1.21.1, have attempted to disable any extensions (this didn't fix anything), and have made sure I added the JS code to my MediaWiki:Common.js.