Jetpack Infinite Scroll Not Working

Question

The infinite scroll works well when I'm on my localhost. It also works when I install my theme to my website to test. But when I install the theme on my client's WP installation, it doesn't work any more. I can't figure out why that would be the case.

if ( ! function_exists( 'swill_setup' ) ):
    function swill_setup() {

    /**
     * Enable support for the Infinite Scroll
    */

    add_theme_support( 'infinite-scroll', array(
      'container' => 'content',
      'footer'    => false,
      'wrapper'   => true
    ) );
  }
endif; // theme setup

add_action( 'after_setup_theme', 'swill_setup' );

I have a content.php file too:

<article>
  // the loop (too long to include here, but you get the picture)
</article>

Which I call like this:

if ( $the_query->have_posts() ) while ( $the_query->have_posts() ) : $the_query->the_post();

  get_template_part('content', get_post_format());

endwhile;

Why would it be so selective on where it works? I'm puzzled because it seems to work on other servers.