posts_per_page not having any effect

Hi, I’m using Jetpack’s Infinite Scroll on a custom theme and it’s working in general but I’m having a problem with the posts_per_page argument.

Here’s my setup code:

function mytheme_render_infinite_scroll() {
		// loading different content templates depending on what type of page is being viewed
		while ( have_posts() ) : the_post();
				if ('mytheme_portfolio' == get_post_type() && !is_search()) :
					get_template_part( 'content', 'archive-portfolio' );
				elseif ( is_search() ) :
					get_template_part('content','search');
				else :
					get_template_part( 'content', get_post_format() );
				endif;
		endwhile;
	}

	function mytheme_jetpack_setup() {
		add_theme_support( 'infinite-scroll', array(
			'container'      => 'content',
			'footer_widgets' => 'footer-widgets',
			'type'           =>	'click',
			'render'         => 'mytheme_render_infinite_scroll',
			'wrapper'        => true,
			'posts_per_page' => 10
		) );
	}
	add_action( 'after_setup_theme', 'mytheme_jetpack_setup' );

As you can see I’m using 'type' => 'click' and have a custom function for render which gets different templates depending on what post-type is being viewed or whether search is being viewed. That is all working fine though.

Basically the problem is the 'posts_per_page' => 10 line is not having any effect. The number of posts showing on my pages relates to the number set for the “Blog pages show at most X posts” setting in Settings -> Reading in the WP admin panel, which is currently set to 5, not the 10 that I want.

I’ve tried looking here http://jetpack.me/support/infinite-scroll/ but couldn’t find anything to help.

I’m not sure if it’s worth noting but I have a message in Settings -> Reading which says:

“To infinity and beyond…We’ve disabled this option for you since you have footer widgets in Appearance → Widgets, or because your theme does not support infinite scroll.”

I thought this probably wasn’t relevant though, as I said the infinite scroll is working for me but with 'type' => 'click', I think the above message has something to do with that.

I have deactivated all other plugins and also tried this in Twenty Thirteen theme, I get the same problem in that too.

I’m using Jetpack 2.7.

http://wordpress.org/plugins/jetpack/