Bidirectional @OneToOne persistence

I am starting with JPA and EclipseLink and did some experiments. But results are a little unexpected for my understanding. Here for example I have a bidirectional relation between two entities:

@Entity
@Table(name = "student")
public class Student {
 
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;
 
    private String name;
 
    @OneToOne(mappedBy = "student", cascade = CascadeType.ALL, orphanRemoval = true, fetch = FetchType.LAZY)
    private Tuition tuition;

@Entity
@Table(name = "tuition")
public class Tuition {
 
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
 
    private Long fee;
 
    // Que columna en la tabla Tuition tiene la FK
    @JoinColumn(name = "student_id")
    @OneToOne(fetch = FetchType.LAZY, cascade = CascadeType.ALL)
    private Student student;

I have created two tests to check persisting both entities from both sides. When I try to persist from one side it works OK, both entities are persisted. But when trying to do the same from the other side Student in Tuition have a null value

Here are the tests:

@FixMethodOrder(MethodSorters.NAME_ASCENDING)
public class Jpa1to1Bidireccional {

    private static final String PERSISTENCE_UNIT_NAME = "JPA_PU";
    private EntityManagerFactory factory;

    @Before
    public void init() throws Exception {
        factory = Persistence.createEntityManagerFactory(PERSISTENCE_UNIT_NAME);
    }

    @Test
    public void testCase_1() {
        System.out.println("Testcase_1 executes");
        EntityManager em = factory.createEntityManager();

        // Begin a new local transaction so that we can persist a new entity
        em.getTransaction().begin();

        Student s = new Student();
        s.setName("Pirulo");
        Tuition t = new Tuition();
        t.setFee(2134L);
        s.setTuition(t);

        em.persist(s);

        // Commit the transaction, which will cause the entity to // be stored in the
        // database
        em.getTransaction().commit();
        em.close();
    }

    @Test
    public void testCase_2() {
        System.out.println("Testcase_2 executes");
        EntityManager em = factory.createEntityManager();

        em.getTransaction().begin();

        Student s = new Student();
        s.setName("Cachilo");
        Tuition t = new Tuition();
        t.setFee(3134L);
        t.setStudent(s);

        em.persist(t);
        em.getTransaction().commit();
        em.close();
    }

Any help to understand what is going on, will be very welcomed. Regards,