Order product ID field returns "0" in Views
I've also experienced this issue by creating hook_views_data_alter adding  the following code into it:

$data['uc_order_products']['order_product_id']['field'] = array(
    'handler' =&gt; 'views_handler_field_numeric',
);


I have noticed that the order_product_id had no handler so since the return of this field is the ordered product id I just went ahead and used the handler that comes with Views views_handler_field_numeric.

If you'd like, I bunched some additions related to the order product id field in my custom module in Ubercart-Add-ons.