Content of TextArea disappears either after resizing the window or maximizing it. It seems that it happens when TextArea contains a lot of text and scrollbar is visible (problem doesn't appear when scrollbar is at top). I could reproduce this issue on three computers using following code (I removed text variable definition - it has about 7000 characters):

        TextArea area = new TextArea();
        area.setWrapText(true);
        area.appendText(text);

        VBox root = new VBox();
        VBox.setVgrow(area, Priority.ALWAYS);
        root.getChildren().add(area);
        Scene scene = new Scene(root, 400, 400);
        primaryStage.setScene(scene);
        primaryStage.show();