"Change in Document Total Amount" attribute in purchasing approvals (PO Document Header Attribute)

Summary:

How this attribute calculates the change in total amount. We have an approval rule based on this, but it is not working as expected.

Content (please ensure you mask any confidential information):

We have a purchase order PO approval rule that if Total amount (Order amount +Tax) amount is changed on a PO through change order, we should reject it.

Change Order='Y' and Change in Document Total Amount>0. Please ignore other attributes in the SS.

Even though, the amount is not changed on the PO (even Showing as Amount Changed=0 on UI), this rule is rejecting the Change Order.