get_circuits() of Stem library returns an empty list

Question

When I execute controller.get_circuits(), I get an empty list. How could this be?

with stem.control.Controller.from_port(port=9151) as controller:
  controller.authenticate()
  controller.signal(Signal.NEWNYM) # get new tor identity
  circs = controller.get_circuits()

  for circ in controller.get_circuits():
    print(circ.id)
  print(len(circs))
  print(circs[1].id)