Sales order not invoiced for Foreign customers x++

Hi,

Below is code written in a runnable class to post an invoice. This code works fine and the sales order is invoiced if the customer is not a foreign customer.

However, the code is not working and status remains "Delivered" if the customer is a foreign customer. If I post the invoice from the sales order form, it is getting invoiced.

Foreign customer: "Foreign customer" field in "General" section of "Tax Information" tab in customer form

Any guidance please.

//Invoicing the sales order
        SalesFormLetter formLetterObj;
        formLetterObj = SalesFormLetter::construct(DocumentStatus::Invoice);
        formLetterObj.update(SalesTable::find("XXXX-000092"));