Wordpress' more tag not working for static pages

Yes, I know about the global $more variable trick but it didn't work out for me.

So here's a quick function to show a static page by ID until the WP more tag:

 function get_post_content_and_title_until_more_tag($post_id){
    // getting the post's content by id
    $current_post = get_post($post_id);

    $title = $current_post->post_title;
    $link = get_permalink($post_id);

    $raw_content = $current_post->post_content;

    // look for the more tag
    $splitted_content = split("<!--more-->", $raw_content);
    // just in case there's no more tag
    $before_more_tag_text = $raw_content; 

    if ( count($splitted_content) > 0 ) {
        // it's there, take the first part only
        $before_more_tag_text = $splitted_content[0];
    }

    // don't forget to apply the 'the_content' filter
    $content = apply_filters(
        'the_content', $before_more_tag_text
    );

    return sprintf(
        '<h3 class="header">%s</h3>
        <div class="wysiwyg">
            %s
        </div>
        <a class="more" href="%s">more...</a>',
        $title, $content, $link
    );
}