For a Category landing page that only shows each ‘product_cat’ image that links to a separate page for each category, I have the following template enclosed.
It doesn’t use $term->term_taxonomy_id but rather $term->term_id. Not sure if it will help, but look it over for differences from what you have.
<?php
/**
* Product taxonomy template
*/
?>
<?php global $wp_query; ?>
<?php get_header('shop'); ?>
<?php do_action('jigoshop_before_main_content'); ?>
<?php $term = get_term_by( 'slug', get_query_var( $wp_query->query_vars['taxonomy'] ), $wp_query->query_vars['taxonomy'] ); ?>
<h1 class="page-title"><?php echo wptexturize($term->name); ?></h1>
<?php echo wpautop(wptexturize($term->description)); ?>
<?php
$args = array(
'orderby' => 'name',
'order' => 'ASC',
'child_of' => $term->term_id,
);
$categories = get_terms( 'product_cat', $args );
?>
<?php if ( sizeof( $categories ) ) : ?>
<div class="product-list">
<ul>
<?php foreach ( $categories as $category ) :
$term = get_term_by( 'id', $category->term_id, 'product_cat' );
if ( ! empty( $term )) :
$title = $term->name;
$thumb = jigoshop_product_cat_image( $term->term_id );
if ( $thumb['thumb_id'] )
$thumb_image = wp_get_attachment_image( $thumb['thumb_id'], 'shop_small' );
else
$thumb_image = jigoshop_get_image_placeholder( 'shop_small' );
?>
<li class="product">
<a href="https://wordpress.stackexchange.com/questions/123930/<?php echo get_term_link( $term->slug,"product_cat' ); ?>" title="<?php echo $title; ?>">
<div class="image-wrap">
<?php echo $thumb_image; ?>
<span class="info-icon"></span>
</div>
<p><strong>
<?php echo ( strlen( $title ) > 70 ) ? substr( $title , 0, 70) . '...' : $title; ?>
</strong></p>
</a>
</li>
<?php endif; ?>
<?php endforeach; ?>
</ul>
</div>
<div class="clear"></div>
<?php else : ?>
<?php jigoshop_get_template_part( 'loop', 'shop' ); ?>
<?php do_action('jigoshop_pagination'); ?>
<?php endif; ?>
<?php do_action('jigoshop_after_main_content'); ?>
<?php do_action('jigoshop_sidebar'); ?>
<?php get_footer('shop'); ?>