I'm working with the accounting module and when I create draft vendor bills and click "Validate" it always moves the bill directly to Paid. I have a blank database with only the Accounting and Finance module installed and it works correctly. It moves the invoice from Draft to Open after validation.
I also have no problem with invoices created from sales orders. It only occurs with vendor bills.
Has anyone experienced a similar problem? I am assuming it must be a configuration setting or a specific addon that is causing the issue. We have no third party addons installed outside of what ships with Odoo 9 Enterprise.