Why when I set query author to current user id disappears meta boxes?

I want other users in custom post types named “xyz” to see only their posts. I did it with this function:

add_filter('pre_get_posts', 'posts_for_current_author');

function posts_for_current_author($query) {

	if(!current_user_can('administrator')) {
	global $user_ID;
		$query->set('author',  $user_ID);
	}
	return $query;
}

But the problem is that they dont see custom fields. How can that be?
Maybe someone has the same issue?