Why workflow event handler does not do its job?

I followed this guide community.dynamics.com/…/developing-a-product-approval-workflow-in-dynamics-ax-2012.aspx step by step to create workflow to be able to approve items.

At the end the part of workflow is working just partially. The workflow is visible, it is changing state of item from “NotSubmitted” to “Submitted” extendingdynamicsax.com/…/ but it looks like the the method completed extendingdynamicsax.com/…/ is never called so it does not change the status to Approved.

When the workflow is canceled the status is changed to “Rejected” so it is little weird.

So my question is: Which part of AX workflow from that guide calls the method completed on workflowEventHandler?