zawiw

I added a solution for this to list_cat_posts.php

Replace Line 62:
$category = 'cat=' . $atts['id'];

by:

if (strpos($atts['id'],'+')){
	$category = explode('+',$atts['id']);
	$category_criteria = 'category__and';
}else{
	$category = explode(',',$atts['id']);
	$category_criteria = 'category';
}

And replace Line 75:

$catposts = get_posts($category.'&numberposts=' . $atts['numberposts'] .
				'&orderby=' . $atts['orderby'] .
				'&order=' . $atts['order'] .
				'&exclude=' . $atts['excludeposts'] .
				'&tag=' . $atts['tags'] .
				'&offset=' . $atts['offset'] );

by:

$catposts = get_posts(array(
				$category_criteria => $category,
				'numberposts' => $atts['numberposts'],
				'orderby' => $atts['orderby'],
				'order' => $atts['order'],
				'exclude' => $atts['excludeposts'],
				'tag' => $atts['tags'],
				'offset' => $atts['offset'] ));

Hope this helps and finds its way into the official plugin version