The chevron view, can be enabled by including the section : pyDisplayStages in your harness rule.
But here you have mentioned screenflow.
Ideally, concept of screenflow, is that, it is just a flow with single assignment, on which a user can perform an action .
If you run the screenflow , standalone, you could see the assignments inside it as below :
If you have included, this screenflow in any of the case,and if you want to display the chevron view for that casetype, you can show it by including the section pyDisplayStages in the corresponding harness rule, so that it gets displayed as below: