I am having issue while running with Flow within Flow which has Parameter that are determined at run time.

with Flow("MasterFlow") as master_flow:
    cobdate = Parameter("cobdate")
    staging_area = FlowRunTask(flow_name='staging_area',
                               parameters=dict(cobdate=cobdate),
                               project_name="SubFlow")
    business_logic_layer = FlowRunTask(flow_name='business_logic_layer',
                                       project_name="SubFlow")
    data_mart = FlowRunTask(flow_name='data_mart',
                            project_name="SubFlow",
                            wait=True)
    staging_area.set_downstream(data_mart)
    business_logic_layer.set_downstream(data_mart)