3317056 - Able to change a Purchase Order under approval - MEPO 173 missing

After the SAP Upgrade to S4 Hana 2021, end-users are able to change quantity on a Purchase Order under approval. You expect the system to issue the message "Purchase order 'xxx' is in approval. You can only display it, not edit it." (MEPO 0173) however it is missing.

• Materials Management (MM)
• SAP ERP Central Component
• SAP ERP
• SAP enhancement package for SAP ERP
• SAP enhancement package for SAP ERP, version for SAP HANA
• SAP S/4HANA
• SAP Fiori 

Purchase Order, under release, PO release, MEPO 173, S4CORE 106 , KBA , MM-FIO-PUR-PO-WFL , Purchase Order Workflow , MM-PUR-PO , Purchase Orders , MM-FIO-PUR-PO , Fiori UI for Purchase Orders , Problem