[BUG] UI should show default value when using `Enum`

[SaraRegibo]

In the CSL UI (see plato-test-scripts), I want to implement the task to switch on the camera:

@exec_ui(display_name="Switch ON",
         icons=(ICON_PATH / "n1-camera-swon.svg", ICON_PATH / "n1-camera-swon-selected.svg"))
def switch_on_camera(image_cycle_time: float = 25, svm_nom: IntSwitch = IntSwitch.ON,
                     svm_red: IntSwitch = IntSwitch.OFF):

In despite of svm_red being set to "OFF" by default, the UI displays "ON" when you open the task.