Custom column with custom field

Hi, I’m using premium plugin version and I want to add custom column (named ‘MyColumn’) in the invoice template, with product custom field value when there’s any, and I tried with:

add_filter('wf_pklist_product_table_additional_column_val', 'wt_pklist_add_custom_col_vl', 10, 6);

function wt_pklist_add_custom_col_vl($column_data, $template_type, $columns_key, $_product, $order_item, $order) {

	$customField = get_field('custom_field_name');

	if($columns_key == 'MyColumn') {
		$column_data = implode( ', ', $customField );
	}
	return $column_data;
}

And this is how I added a column in the invoice template editor: http://prntscr.com/4EqSRd1NPevu

But the column row is always empty. I’m using implode since the field it’s an array with multiple values in some fields (and in some is a single value or without value).

Any suggestion on how to achieve this?