get all posts from a custom post type

I’m trying to get all posts from a particular custom post type using the following code:

$auctions = get_posts(array('post_type' => 'auction'));
print_r($auctions);
echo '<select>';
foreach ($auctions as $auction) {
    echo '<option value="' . $auction->ID . '">' . $auction->post_title . '</option>';
}
echo '</select>';

Although the print_r() call shows data, the foreach seems to ignore it and doesn’t print anything. Any ideas?

Any help would be appreciated

print_r() output:

Array (
    [0] => WP_Post Object (
        [ID] => 36
        [post_author] => 1
        [post_date] =>    2013-05-19 10:58:45
        [post_date_gmt] => 2013-05-19 08:58:45
        [post_content] =>
        [post_title] => My Title
        [post_excerpt] =>
        [post_status] => publish
        [comment_status] => closed
        [ping_status] => closed
        [post_password] =>
        [post_name] => my-title
        [to_ping] =>
        [pinged] =>
        [post_modified] => 2013-05-24 09:55:53
        [post_modified_gmt] => 2013-05-24 07:55:53
        [post_content_filtered] =>
        [post_parent] => 0
        [guid] => http://domain.com/?post_type=auction&p=36
        [menu_order] => 0
        [post_type] => auction
        [post_mime_type] =>
        [comment_count] => 0
        [filter] => raw
    )   
) 

You can use wp_query() for this to work

$args = array(
        'post_type' => 'auction',
        'posts_per_page' => -1
    )
$query = new WP_Query($args);
if ($query->have_posts() ) : 
    echo '<select>';
    while ( $query->have_posts() ) : $query->the_post();
            echo '<option value="' . get_the_ID() . '">' . get_the_title() . '</option>';
    endwhile;
    echo '</select>';
    wp_reset_postdata();
endif;

Documentation for WP_Query https://codex.wordpress.org/Class_Reference/WP_Query