How to remove Edit option for open Purchase Orders

Summary: Hello Oracle Experts! Our client have a requirement to disable the Edit option for approved Purchase Orders. They don't wish to edit the POs once it is moved to OPEN status. How to bring in this control. Tried sandbox option with binding condition #{bindings.DocumentStatus.inputValue} == 'OPEN', though the document is in OPEN status, the condition throws False, not able to understand that.

Also when we publish that sandbox, the Edit option gets disabled entirely for all the PO Statuses. That is not the expected behaviour.

We also tried controlling using the Custom Role option, by removing the Edit option privilege's, still that also removes the Edit option for all the PO statuses. But that is known that we cannot control Edit option based on statuses using Roles.