WPMU was stripping out any html I put into a post so the subscribe form for updates wasn’t showing up. Even using a shortcode wouldn’t work until I removed the filter responsible.
Edited functions.php to add shortcode
add_shortcode('shortcodename','functionnameinfunctions.php');
function shortcodename($atts,$content=null){
remove_filter(‘the_content’,'wp_filter_post_kses’);
$return = ‘
‘;
return $return;
}
Prevents all shortcodes from being executed in the theme, just the ones I want.