Restrict Edit/Cancel Action for Processed Requisitions (PO or TO is created)

Summary:

We are using Redwood SSP and need to prevent users from editing or cancelling a requisition (or requisition lines) once it has been processed — i.e., when a Purchase Order or Transfer Order has already been created.

We created a custom role and removed the following privileges:

• Cancel Purchase Order as Procurement Requester
• Change Purchase Order as Procurement Requester

Despite removing these privileges, users can still edit and cancel the requisitions.

We also tried hiding the Edit and Cancel actions using Visual Builder Studio (VBS) using different conditions but none of them are working.

Could you please advise on the best way to achieve this? Any working VBS business rule examples, specific conditions, or alternative approaches would be greatly appreciated. Thanks in advance for your help!