javafx User interface not updating? - user-interface

Question

I'm new to JavaFX.
I'm building a GUI for a project of mine, and I have a problem with it -
it seems that once I show my UI it stops updating.
In my case, it supposed to update a fill colour for a circle but it does not.
I tried to move the line:
someCircleId.setFill(color));
to be above the line:
Main.stage.show();
in the initialize function in my code and it did change the color of
the certain circle.
public class UIController implements Initializable {
public UIController() {
fillMap();
}
#Override
public void initialize(URL location, ResourceBundle resources) {
Main.stage.show();
}
#FXML
public void pressExitButton() {
Main.dropDBSchema();
System.exit(0);
}
public void changeCircleColor(String circleKey, Color color) {
Platform.runLater(
() -> {
Circle circle = this.circles.get(circleKey);
PauseTransition delay = new PauseTransition(Duration.seconds(10));
delay.setOnFinished(event -> circle.setFill(color));
delay.play();
}
);
}
}
And this is the class that uses these functions:
public class MonitoringLogicImpl implements MonitoringLogic {
public void updateUI(UUID flowUUID, String sender, String receiver, DATA_STATUS status){
String key = flowUUID.toString()+"_"+sender+"_"+receiver;
Color color = this.uiController.getColorAccordingToStatus(status);
this.uiController.changeCircleColor(key, color);
}
}
This is the FXML initialization :
public void start(Stage stage){
this.stage = stage;
FXMLLoader loader = new FXMLLoader();
try {
loader.setLocation(getClass().getResource("/UserInterface.fxml"));
this.root = loader.load();
} catch (IOException e) {
e.printStackTrace();
} catch (Exception e){
e.printStackTrace();
}
stage.setTitle("Troubleshooting project");
stage.setScene(new Scene(root, 900, 700));
stage.show();
}
I created my UI using Scene-Builder tool.