Purchase Order Re-approval Policy and Workflow

I have the following scenario:

After purchase requisition approval and PO creation, I want to make sure that the Purchase Order will go for re-approval if the fields unit price and quantity are changed.


At the moment ALL PO changes require re-approval, e.g. changes to the confirmed delivery date.

Current Setup:

Purchasing Policy for PO re-approval is active in the relevant company and the values Purchase Order Line Price Unit and Purchase Order Line Quantity are selected to require re-approval. All other fields are not selected.

Workflow for PO automatic actions is set to Purchase Order Requires Re-Approval is value = NO > Auto complete action: Approve. The approval step, in case auto complete does not apply, is set up to go to a specific user. I have also tried the same set up with a conditional decision rather then just using the workflow element Approve Purchase Order

Looking at the workflow history of the purchase orders I have tested the workflow seems to ALWAYS evaluate the automatic action to FALSE so that re-approval is required regardless of what fields are being updated.

I am unsure if I am missing something in the policy or the workflow or both? Do I require a purchase order line workflow to make this work?

Thank you!