Japanese

Environment: Java SE (Java 8 Update 40) on Windows 7

  tracker = new TrackBackupService();
  tracker.setOnReady((WorkerStateEvent e) -> {
  backupUserCancelled = false;
  });

  tracker.setOnScheduled((WorkerStateEvent e) -> {
  backupProgressBar.progressProperty().bind(tracker.progressProperty());
  backupPathInProcessingLabel.textProperty().bind(tracker.pathInProcessingProperty());
  backupWorkDoneLabel.textProperty().bind(tracker.workDoneProperty().asString("%.0f"));
  backupTotalWorkLabel.textProperty().bind(tracker.totalWorkProperty().asString("%.0f"));
  backupSelectTargetButton.disableProperty().bind(tracker.runningProperty());
  backupWarningMessageLabel.visibleProperty().bind(tracker.runningProperty());
  backupStartButton.disableProperty().bind(tracker.runningProperty());
  backupStopButton.disableProperty().bind(Bindings.not(backupStartButton.disableProperty()));
  backupSizeLabel.textProperty().bind(tracker.totalSizeProperty());
  backupDirectoryCountLabel.textProperty().bind(tracker.directoryCountProperty().asString());
  backupFileCountLabel.textProperty().bind(tracker.fileCountProperty().asString());
  backupResultLabel.textProperty().bind(tracker.messageProperty());
  });

Run this code there are times when the progress bar is not updated as well.

However, the progress bar is updated when you display again window after you minimize the window.