@DheerajK7369 Hi DheerajK, do you mean returning to another stage instantaneously? I would recommend to submit first the flow action, then in the flow use the change stage shape.
If you want to change the stage on dropdown change you may call the pxChangeStage activity and refreshing the harness. You may need to finish the current assignment first in order to not to leave an open assignment in your worklist.
But if you can, try to follow the standard way using flows and smart shapes.
Oh, by the way, if you want to return to the previous stage (strictly previous), you can use the pyWorkPage.pxStageHistory list to get the last stage.