It is assigned in another file that calls this one :
if(have_rows('mb_collection_strates')):
while(have_rows('mb_collection_strates')): the_row();
$layout = get_row_layout();
echo clrz_get_template_part('collections-level-one', $layout);
endwhile;
endif;
NB : the second nested repeater loop call just the radio button mb_hairstyle_product_position and does find any other field
