Getting NullPointerException in spinner in Android unit test

I have an activity with a spinner, and I load spinner items from server. My problem is if I run the whole ApplicationTest class my spinner is null, but if I run only the testEditCard method the spinner isn't null and I don't know what is wrong.

Here is my ApplicationTest.class:

public class ApplicationTest extends ActivityInstrumentationTestCase2<MainActivity> {

private MainActivity mainActivity;
private Button showLibBtn;
private String token;
private LibraryCardsActivity libraryCardsActivity;
private LibraryEditCard libraryEditCard;
private CustomButton btnEditCard;

public ApplicationTest() {
    super(MainActivity.class);
}

@Override
public void setUp() throws Exception {
    super.setUp();
    setActivityInitialTouchMode(false);
    mainActivity = getActivity();
    showLibBtn = (Button) mainActivity.findViewById(R.id.showLib);
    token = mainActivity.token;
    Thread.sleep(10000);
}

@MediumTest
public void testCardsActivity() throws Exception{
    loadLibraryCardsActivity();
    final CustomEditText inputET = (CustomEditText) libraryCardsActivity.findViewById(R.id.inputET);
    assertNotNull("cvvInputET is null", cvvInputET);
    /**
     * Insert CVV code.
     */
    final String inputValue = "1234";
    libraryCardsActivity.runOnUiThread(new Runnable() {
        @Override
        public void run() {
            inputET.setText(inputValue);
        }
    });
    CustomButton btnOk = (CustomButton) libraryCardsActivity.findViewById(R.id.cardsActivitybtnOk);
    assertNotNull("btnOk is null", btnOk);
    TouchUtils.clickView(this, btnOk);
    Thread.sleep(5000);
    assertEquals("", inputET.getText().toString());
}

@MediumTest
public void testEditSelectedCard() throws Exception{
    /**
     * Load LibraryCardsActivity
     */
    loadLibraryCardsActivity();
    Thread.sleep(5000);
    final Spinner spCards = (Spinner) libraryCardsActivity.findViewById(R.id.spCards);
    assertNotNull("spCards is null", spCards);
    libraryCardsActivity.runOnUiThread(new Runnable() {
        @Override
        public void run() {
            spCards.setSelection(2);
        }
    });
    Thread.sleep(4000);
    CardModel cardModel = (CardModel) spCards.getSelectedItem();
    assertNotNull(cardModel);
    btnEditCard = (CustomButton) libraryCardsActivity.findViewById(R.id.cardsActivitybtnEditCard);
    /**
     * Load LibraryEditCard activity
     */
    loadEditCardActivity();
    CustomTextView cardNumber = (CustomTextView) libraryEditCard.findViewById(R.id.editCardNumberTV);
    assertNotNull("cardNumber is null", cardNumber);
    assertEquals(cardModel.getCardNumber(), cardNumber.getText().toString());
}
   @Override
public void tearDown() throws Exception {
    super.tearDown();
}

private void loadLibraryCardsActivity() throws Exception{
    /**
     * Load LibraryCardsActivity
     */
    Instrumentation.ActivityMonitor cardsMonitor = getInstrumentation().addMonitor(LibraryCardsActivity.class.getName(), null, false);
    mainActivity.runOnUiThread(new Runnable() {
        @Override
        public void run() {
            showLibBtn.performClick();//TouchUtils.clickView(this, showLibBtn);
        }
    });
    Thread.sleep(10000);
    libraryCardsActivity = (LibraryCardsActivity) cardsMonitor.waitForActivity();
    assertNotNull("libActivity is null", libraryCardsActivity);
    btnEditCard = (CustomButton) libraryCardsActivity.findViewById(R.id.cardsActivitybtnEditCard);
    getInstrumentation().removeMonitor(cardsMonitor);
}

private void loadEditCardActivity() throws Exception{
    /**
     * Load LibraryEditCard activity
     */
    Instrumentation.ActivityMonitor editMonitor = getInstrumentation().addMonitor(LibraryEditCard.class.getName(), null, false);
    libraryCardsActivity.runOnUiThread(new Runnable() {
        @Override
        public void run() {
            btnEditCard.performClick();
        }
    });
    Thread.sleep(4000);
    //TouchUtils.clickView(this, btnEditCard);
    libraryEditCard = (LibraryEditCard) editMonitor.waitForActivityWithTimeout(3000);
    assertNotNull("libEditCardActivity is null", libraryEditCard);
    getInstrumentation().removeMonitor(editMonitor);
}
}

And I am getting NullPointerException for spinner in testEditSelectedCard() method.