Hi Paul, firstly welcome to the Dynamics User Group. Good to see more Australian’s joining, even East Coasters [;)]
Looking at your issue, the standard Navision Cheque processing ONLY looks at posted Purchase Invoices, it does not look at Purchase Orders. So the issue of Opening and Releasing, sounds like a modification that your partner has done for you. Or it could be an APAC customization, but since leaving OZ, I really have not looked at the Australian version, so can’t be certain.
Do you know if this area was customized for your company?