[Plugin: WP-polls] Vote button not working for guests

Same behavior described here:
http://ww.wp.xz.cn/support/topic/vote-button-no-longer-working?replies=6

Can select radio buttons, but “VOTE” button is non-functional. Clicking does nothing.

Difference: ^^^ this behavior is only true for non-WP users. For the authors on our site, it works fine. For readers, it’s non-functional. The option for “who can vote” is set to “Registered Users and Guests”, so it’s not that.

The linked solution didn’t work.

Per Chrome Developer tools, there’s no difference in the actual code between when logged in or incognito. The only difference is that incognito I get the error:

Uncaught ReferenceError: poll_vote is not defined
(5x)

Here’s an example of a post with a poll (scroll down)
http://hooniverse.com/2013/08/16/hooniverse-obscure-muscle-car-garage-the-1968-pontiac-grand-prix/

I believe I have WP-supercache set to show non-cached files to logged in users. Would caching be causing this error?

Using Atahualpa theme.