DataTable component of primefaces is not updated correctly

I try to refresh the dataTabale component of primefaces when I delete a record from the table, however, when I click on the delete button, sometimes the table is updated and sometimes not, then I have to manually refresh the entire page to see the change in the dataTable component.

I noticed something curious, every time I upload the application to the server again (wildfly 8.2) and start with the 4 record (Hulk), the dataTable component is updated immediately, if I start with the first or last record, I have to press the Delete button several times, until the component is refreshed.

Record to be deleted.

Registration removed

  <h:form id="form">
        <p:dataTable id="studentsDataTable"
                     value="#{studentsController.students}"
                     var="student"
                     rowKey="#{student.username}"
                     selection="#{studentsController.studentSelected}"
                     selectionMode="single">

            <!--Header-->
            <f:facet name="header">
                Spanish Academy : Students' List
                <p:button value="Add Student" outcome="new_student" />
            </f:facet>

            <p:column headerText="Username">
                <h:outputText value="#{student.username}" />
            </p:column>
            <p:column headerText="Firstname">
                <h:outputText value="#{student.firstname}" />
            </p:column>
            <p:column headerText="Lastname">
                <h:outputText value="#{student.lastname}" />
            </p:column>
            <p:column headerText="Edit" style="width:50px">

            </p:column>
            <!--Footer-->
            <f:facet name="footer">
                <p:commandButton value="Delete" actionListener="#{studentsController.deleteStudent}"  icon="ui-icon-close" process="@form" update=":form:studentsDataTable"/>
                <p:spacer height="5px;"/>
            </f:facet>
        </p:dataTable>

    </h:form>

StudentController (ManagedBean) - Web Layer / Presentation

 Named
@ApplicationScoped
public class StudentsController implements Serializable {

@EJB
private StudentService studentService;

private List<Student> students;

private Student studentSelected;

@PostConstruct
public void init() {
    students = studentService.getAllStudents();
    studentSelected = new Student();
}

public void deleteStudent() {
    studentService.deleteStudent(this.studentSelected);
    this.studentSelected = null;
    //List update
    this.init();
}

public StudentService getStudentService() { return studentService; }

public void setStudentService(StudentService studentService) { 
this.studentService = studentService; }

}

EJB (services) - Business Layer

@Stateless
public class StudentServiceImpl implements StudentService {

@Inject
private StudentDao studentDao;

...

@Override
public void deleteStudent(Student student) { 
studentDao.remove(student); }
}

EJB (Dao) - Data Access Layer

@Stateless
public class StudentDaoImpl implements StudentDao {

...
    @Override
    public void remove(Student student) {
        for (Student studentInDB: StudentsDB.students) {
            if(student.getUsername().equals(studentInDB.getUsername())) {
                StudentsDB.students.remove(studentInDB);
            }
        }
    }
}

Static database

public class StudentsDB {
public static List<Student> students;

static {
    Student student;
    students = new ArrayList<>();

    student = new Student("Snake", "John", "Smith");
    students.add(student);
    student = new Student("Cowboy", "George", "Lopez");
    students.add(student);
    student = new Student("Batman", "Luis", "Williams");
    students.add(student);
    student = new Student("Hulk", "Miguel", "Woods");
    students.add(student);
    student = new Student("Prime", "Jeniffer", "Fierro");
    students.add(student);
}
}

Student Model (Java Bean Simple)

public class Student {

private String username;
private String firstname;
private String lastname;
private Date birthDate;
private String country;
private String city;
private String street;
private Integer zipCode;
private Integer phoneNumber;
private String email;
private boolean acceptTerms;

public Student() { }

public Student(String username, String firstname, String lastname) {
    this.username = username;
    this.firstname = firstname;
    this.lastname = lastname;
}
...
<!-- getters & setters -->
}

I have tried in many ways, to solve it, however, I have not been able until now, I have read, other problems similar to mine, however, they have not worked for me.

link

Problem when updating datatable component of primefaces

I had even asked the question in stackoverflow in English and they have given me some advice, but they have not worked for me.

link

Any ideas?

Thanks in advance.