Wordpress nested loop, cannot remove meta_key from the query - php

Question

I have two custom posts types A and B, linked together with a same custom taxonomy.
While looping through A posts with the "default" loop, I want for each A to get all B with the same taxonomy.
The code looks like this:
<?php if(have_posts()): while(have_posts()): the_post(); ?>
<?php
$A_Bs=get_the_terms( $post->ID, 'A_B');
?>
<?php if($A_Bs!=false && count($A_Bs)>0):?>
<?php
$A_B=$A_Bs[0];
$args = array(
'post_type' => 'B',
'tax_query' => array(
array(
'taxonomy' => 'A_B',
'field' => 'term_id',
'terms' => $A_B->term_id,
),
),
);
$loop = new WP_Query($args);
$saved_post=$post;
?>
<?php while ($loop->have_posts()) : $loop->the_post();?>
blabla
<?php endwhile;?>
<?php $post=$saved_post;?>
<?php endif;?>
<?php endwhile; endif;?>
But the sub-loop is always empty. The reason is, in the query_vars I have these two guys:
'meta_key' => string 'position' (length=8)
'orderby' => string 'meta_value_num' (length=14)
and I can't get rid of them. I never specified this ordering anywhere and my B posts don't have this custom field.
It's generating this line in the SQL query:
aaaa_postmeta.meta_key = 'position'
and prevent me to list the posts.
I tried to play with the $args, removing the tax_query and changing the post_type but it's always the same.
Thank you for your time !

Answer 1

Sorry I just realized after hours that I have the following thing in functions.php
function order_by_position($query){
if(is_post_type_archive( 'A')||is_post_type_archive( 'C')||is_post_type_archive( 'D')){
$query->query_vars['meta_key']="position";
$query->query_vars['orderby']="meta_value_num";
}
return $query;
}
add_action( 'pre_get_posts', 'order_by_position' );
It's much more logical now.
Sorry for disturbing.