Hi,
Well, the issue is that you're missing the whole code to display custom order fields on the invoice:
$fieldsClass = hikashop_get('class.field');
$fields = $fieldsClass->getFields('display:invoice=1',$this->order,'order');
if(!empty($fields)){ ?>
<tr>
<td>
<fieldset class="hikashop_order_custom_fields_fieldset">
<legend><?php echo JText::_('ADDITIONAL_INFORMATION'); ?></legend>
<table class="hikashop_order_custom_fields_table adminlist" cellpadding="1" width="100%">
<?php foreach($fields as $fieldName => $oneExtraField) {
?>
<tr class="hikashop_order_custom_field_<?php echo $fieldName;?>_line">
<td class="key">
<?php echo $this->fieldsClass->getFieldName($oneExtraField);?>
</td>
<td>
<?php echo $this->fieldsClass->show($oneExtraField,@$this->order->$fieldName); ?>
</td>
</tr>
<?php
}?>
</table>
</fieldset>
</td>
</tr>
<?php
}
You apparently removed it form the view file at one point.