Problem with getting all posts

Hi,

I’m having problems getting ALL posts for my custom post type. I’ve tried using both get_posts() and WP_Query() with no luck. Here is the code (tried both posts_per_page and numberposts parameters).

If I set a number like 200 in posts_per_page, I get 200 posts, when I try 1,000 or -1 it returns empty. What could this be??

Thanks

$stores_args = array(
  'post_type' => 'stores',
  'posts_per_page' => -1,
  'order' => 'ASC',
  'orderby' => 'title'
);

$query = get_posts( $stores_args );