I'm using human made's custom meta boxes framework (https://github.com/humanmade/Custom-Meta-Boxes). I want to add a select drop down in my metabox wich is populated from the users with multiple roles on my WP site. Referencing this post : http://wordpress.stackexchange.com/questions/39315/get-multiple-roles-with-get-users

I came up with:

 add_filter( 'cmb_meta_boxes', 'users_metabox' );
 
 function eusers_metabox( array $meta_boxes ) {
 
 $prefix = 'user_';
 
 global $wpdb;
 $blog_id = get_current_blog_id();
 
 $user_query = new WP_User_Query( array(
 'meta_query' => array(
 'relation' => 'OR',
 array(
 'key' => $wpdb->get_blog_prefix( $blog_id ) . 'capabilities',
 'value' => 'Administrator',
 'compare' => 'like'
 ),
 array(
 'key' => $wpdb->get_blog_prefix( $blog_id ) . 'capabilities',
 'value' => 'Editor',
 'compare' => 'like'
 )
 )
 ) 
 );
 
 $fields = array(
 array( 
 'id' => $prefix . 'user_sub', 
 'name' => 'Subscriber User', 
 'type' => 'select',
 'use_ajax' => false,
 'options' => $user_query, // this is where you populate the select in metabox
 ),
 );
 
 $meta_boxes[] = array(
 'title' => 'Location Info',
 'pages' => 'em_users',
 'context' => 'normal',
 'priority' => 'high',
 'fields' => $fields
 );
 
 return $meta_boxes; 
 
 }

Works somewhat, but seems to return just capital letters. Any ideas?