You have configured Workflow settings for Purchase Orders , however the workflow is not trigerred during the PO creation. Nothing is sent to My Inbox. Purchase order don´t receive the status in approval.
The flexible workflow has to be fully configured.
1) Activate Flexible workflow for Purchase Orders
APP Manage Your Solution > configure your solution > search for 'flexible workflow' > Activate Flexible Workflow for Purchase Orders > Activate PO type NB.
2) Configure your flexible workflow requirements
App 'Manage Workflows for Purchase Orders'.
3) If you intend to use the option 'Manager of Workflow Initiator' you have to first establish the employee/employer relationship
APP Import employee, to create a valid employee/employer relationship in the system (IEMPLOYMENTMGR)
Once these are set up and activated, when you create PO that meets the criteria defined, the workflow will be sent to My Inbox.
KBA , MM-FIO-PUR-PO , Fiori UI for Purchase Orders , MM-PUR-GF-REL , Release (Approval) , How To