To reproduce:
1. Click the button "Set current page index";
2. Visible buttons are 10 - 14. It is supposed that it would be 11-15.
3. Click the button "Go to beginning".
4. Push right arrow until the button "6" appears;
5. Then click "Set current page index". Now the range is 11 - 15.

It turns out that set current page index shows different button ranges depending on the current state of control.

public void start(Stage stage) {

        HBox root = new HBox(20d);

        final Pagination pg = new Pagination();
        pg.setMaxPageIndicatorCount(5);
        pg.setPageCount(100);
        pg.setMinSize(200.0, 200.0);
        pg.setPrefSize(200.0, 200.0);
        
        Button btn = new Button("Set current page index");
        btn.setOnAction(new EventHandler<ActionEvent>() {
            @Override
            public void handle(ActionEvent t) {
                pg.setCurrentPageIndex(13);
            }
        });
        
        Button btn2 = new Button("Go to beginning");
        btn2.setOnAction(new EventHandler<ActionEvent>() {
            @Override
            public void handle(ActionEvent t) {
                pg.setCurrentPageIndex(1);
            }
        });

        VBox vb = new VBox(3.34);
        vb.getChildren().addAll(btn, btn2);
        
        root.getChildren().addAll(pg, vb);
        
        Scene scene = new Scene(root, 400, 250);

        stage.setScene(scene);
        stage.setTitle(System.getProperty("java.runtime.version") + "; " + System.getProperty("javafx.runtime.version"));
        stage.show();
    }