Board Thread:Support Requests - Getting Technical/@comment-6330346-20130416221731/@comment-10688548-20130417193937

I know you solved your problem, but as for why the old, outdated collapse system works on English wiki...

Your Wikia.js is blank, as is that of the English wiki. So there's no code for the old, outdated collapse system there.

However, Common.js on the English wiki imports the collapse code from the developer wiki. Wikia.js is the set of scripts for the Wikia (default) skin, while Common.js is "common" to the Wikia skin as well as the alternate Monobook skin.