Coauthors Plugin Issue: WP_Query for author, produces no results

I am using the Coauthors Plus plugin and up until now it had worked great for everything I was doing. But now I am trying to show an authors posts on a page that isn’t ‘author.php’. I’m using the following…

$query = "author_name=alicia-munnell&posts_per_page=3";
$posts = new WP_Query($query);
if($posts->have_posts()) {
	while($posts->have_posts()) { $posts->the_post();?>
		<h2><?php the_title(); ?></h2>
	<?php }
} ?>

This code works for certain authors that are the original author of a post, but if an author has never been an original author, then nothing shows up.

How can I get around this and display a coauthor’s posts? Any help is greatly appreciated. Thanks.