Orderby meta_key/meta_value not displaying anything, am I overlooking anything?

I have an issue with my orderby using get_posts(). I want to order in alphabetical order a list by city name using a custom meta field, but it comes back empty. However when I orderby title, the list is displayed with no issues.

I activated WP_DEBUG and no errors or notices were found.

I checked the query in hopes that I was using the wrong meta_key, but everything looks as it should be. Am I missing anything?

SELECT wp_posts.* FROM wp_posts INNER JOIN wp_postmeta ON ( wp_posts.ID = wp_postmeta.post_id ) WHERE 1=1 AND ( wp_postmeta.meta_key = 'ville' ) AND ((wp_posts.post_type = 'ecole' AND (wp_posts.post_status = 'publish' OR wp_posts.post_status = 'private'))) GROUP BY wp_posts.ID ORDER BY wp_postmeta.meta_value DESC

$posts = get_posts( array(
     'post_type' = 'ecole',
     'posts_per_page' = -1,
     'meta_key' = 'ville',
     'orderby' = 'meta_value',
     'order' = 'ASC'
) );


if ( $posts ) {
     foreach ( $posts as $post ):

     List goes here

?php
endforeach;
}