Perform Bulk Billing via Transactions > Sales > Bill Sales Orders: Certain Orders Cannot be Billed

Sometimes on the customer record, billing/shipping address can have duplicate or 2 different names on the Address tab. This can be fixed by making sure that the contact records of the customer record do not have Default Billing Address and Default Mailing Address checked:

 

1.  Open Customer record and click on Edit.
2.  Under Relationships > Contacts subtab.
   
3. Click on Customize View.
4.  On Results tab, add Default Shipping Address & Default Billing Address.
5. Click on Save