New posts dont display

After installing plugin I have the problem that posts are not displaying using get_posts() function as below:

$args = array(
	'posts_per_page'	=> -1,
	'post_type'			=> 'post',
	'offset'			=> 0,
	'category'			=> $category->term_id,
	'post_status'		=> 'publish',
	'meta_key'			=> '_sort_'.$category->term_id,
	'meta_type'			=> 'NUMERIC',
	'orderby'			=> 'meta_value',
	'order'				=>'ASC'
);

$posts = get_posts($args);

I think is that because new posts doesnt have order value. After going to taxonomy order page new posts have order value set to “0” – the same as one of the the other post. After saving the order everything works perfectly.

I think solution will be hook which shifts menu order value in given taxonomy, but I dont know how to achieve that.