[sean-doherty]

This worked for me:

add_action('woocommerce_admin_order_item_values', 'my_woocommerce_admin_order_item_values', 10, 3);
function my_woocommerce_admin_order_item_values($_product, $item, $item_id = null) {

    $colour = get_the_terms( $_product->post->ID, 'pa_colour');
    echo '<td>' . $colour[0]->name . '</td>';
}

Had to go down the route of taxonomy and not get_attribute(). Thanks to this post:

show product meta in order items table in Order Details

[Author]

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