bluezonefishing

I was able to get the search to filter not by the full invoice reference (e.g. prefix/suffix) but only the numeric number using the below code:

add_filter( 'woocommerce_shop_order_search_fields', 'woocommerce_shop_order_search_custom_fields' );

function woocommerce_shop_order_search_custom_fields( $search_fields ) {
    $search_fields[] = '_wcpdf_invoice_number';
    return $search_fields;
}

TO make the results work I have started the numbering as follows:
Invoice = 200001
Credit = 400001
Proform = 600001

It would be great if it could search by the full reference but for now this seems a reasonable work around.

I have tried adding this with the below code in my functions.asp file but it does not identify any results:

add_filter( 'woocommerce_shop_order_search_fields', 'woocommerce_shop_order_search_custom_fields' );

function woocommerce_shop_order_search_custom_fields( $search_fields ) {
    $search_fields[] = 'pdf_invoice_number';
    return $search_fields;
}

Taken from:
https://www.skyverge.com/blog/searching-custom-fields-woocommerce-order-admin/

Is this because the pdf_invoice_number is not stored in the meta_key used by the search filter?

I have the same issue however adding complete delivery details does not resolve the problem for me.

I have the multiple shipping address plugin installed but even when deactivated the shipping address does still not appear.

It only appears to affect orders created using the admin interface, not those created on the front end checkout page.