At the very beginning after startup, we still can't start editing via keyboard, at least not by anything intuitive. All works as expected after having clicked once into a cell or (and this is the unintuitive part) having pressed ctrl-left/ctrl-right once.

/**
 * Can't start editing via keyboard initially.
 * Left-over part of issue RT-38464
 *
 * To reproduce, run example
 * - press down (or any navigation key) to select a row
 * - press F2
 * - expected: editing started
 * - actual: nothing happens
 *
 */
public class TableInitialCellEdit extends Application {
    
    ObservableList<MenuItem> data = FXCollections.observableArrayList(
            new MenuItem("some"),
            new MenuItem("dummy"),
            new MenuItem("data")
            );

    private Parent getContent() {
        TableView<MenuItem> table = new TableView<>(data);
        table.setEditable(true);
        TableColumn<MenuItem, String> text = new TableColumn<>("Text");
        text.setCellValueFactory(new PropertyValueFactory<>("text"));
        text.setCellFactory(TextFieldTableCell.forTableColumn());
        table.getColumns().addAll(text);
        return new BorderPane(table);
    }
    @Override
    public void start(Stage primaryStage) throws Exception {
        primaryStage.setScene(new Scene(getContent()));
        primaryStage.setTitle(VersionInfo.getRuntimeVersion());
        primaryStage.show();
    }

    public static void main(String[] args) {
        launch(args);
    }

}