diff --git a/src/Plugin/Field/FieldWidget/InlineEntityFormBase.php b/src/Plugin/Field/FieldWidget/InlineEntityFormBase.php
index 43e173a..da6a1ab 100644
--- a/src/Plugin/Field/FieldWidget/InlineEntityFormBase.php
+++ b/src/Plugin/Field/FieldWidget/InlineEntityFormBase.php
@@ -315,7 +315,6 @@ abstract class InlineEntityFormBase extends WidgetBase implements ContainerFacto
    *   Form array structure.
    */
   public static function addIefSubmitCallbacks($element) {
-    $element['#element_validate'][] = [get_called_class(), 'validateSaveEntity'];
     $element['#ief_element_submit'][] = [get_called_class(), 'submitSaveEntity'];
     return $element;
   }
@@ -366,7 +365,7 @@ abstract class InlineEntityFormBase extends WidgetBase implements ContainerFacto
    * @param $form_state
    *   The form state of the parent form.
    */
-  public static function validateSaveEntity($entity_form, FormStateInterface $form_state) {
+  public static function submitSaveEntity($entity_form, FormStateInterface $form_state) {
     $ief_id = $entity_form['#ief_id'];
     /** @var \Drupal\Core\Entity\EntityInterface $entity */
     $entity = $entity_form['#entity'];
@@ -383,7 +382,7 @@ abstract class InlineEntityFormBase extends WidgetBase implements ContainerFacto
         'entity' => $entity,
         '_weight' => $weight,
         'form' => NULL,
-        'needs_save' => FALSE,
+        'needs_save' => TRUE,
       );
       $form_state->set(['inline_entity_form', $ief_id, 'entities'], $entities);
     }
@@ -391,27 +390,6 @@ abstract class InlineEntityFormBase extends WidgetBase implements ContainerFacto
       $delta = $entity_form['#ief_row_delta'];
       $entities = $form_state->get(['inline_entity_form', $ief_id, 'entities']);
       $entities[$delta]['entity'] = $entity;
-      $entities[$delta]['needs_save'] = FALSE;
-      $form_state->set(['inline_entity_form', $ief_id, 'entities'], $entities);
-    }
-  }
-
-  public static function submitSaveEntity($entity_form, FormStateInterface $form_state) {
-    $ief_id = $entity_form['#ief_id'];
-    $entity = $entity_form['#entity'];
-
-    if ($entity_form['#op'] == 'add') {
-      $entities = $form_state->get(['inline_entity_form', $ief_id, 'entities']);
-      $item = array_pop($entities);
-      $item['entity'] = $entity;
-      $item['needs_save'] = TRUE;
-      array_push($entities, $item);
-      $form_state->set(['inline_entity_form', $ief_id, 'entities'], $entities);
-    }
-    else {
-      $delta = $entity_form['#ief_row_delta'];
-      $entities = $form_state->get(['inline_entity_form', $ief_id, 'entities']);
-      $entities[$delta]['entity'] = $entity;
       $entities[$delta]['needs_save'] = TRUE;
       $form_state->set(['inline_entity_form', $ief_id, 'entities'], $entities);
     }
diff --git a/src/Plugin/Field/FieldWidget/InlineEntityFormSimple.php b/src/Plugin/Field/FieldWidget/InlineEntityFormSimple.php
index 553605c..102e734 100644
--- a/src/Plugin/Field/FieldWidget/InlineEntityFormSimple.php
+++ b/src/Plugin/Field/FieldWidget/InlineEntityFormSimple.php
@@ -100,7 +100,9 @@ class InlineEntityFormSimple extends InlineEntityFormBase {
         return;
       }
 
-      $values[$submitted_values[$delta]['_weight']] = ['entity' => $entity];
+      $weight = isset($submitted_values[$delta]['_weight']) ? $submitted_values[$delta]['_weight'] : 0;
+
+      $values[$weight] = ['entity' => $entity];
     }
 
     // Sort items base on weights.
diff --git a/src/Tests/InlineEntityFormWebTest.php b/src/Tests/InlineEntityFormWebTest.php
index 050e838..ee449c4 100644
--- a/src/Tests/InlineEntityFormWebTest.php
+++ b/src/Tests/InlineEntityFormWebTest.php
@@ -7,6 +7,7 @@
 
 namespace Drupal\inline_entity_form\Tests;
 
+use Drupal\Core\Field\FieldStorageDefinitionInterface;
 use Drupal\simpletest\WebTestBase;
 
 /**
@@ -29,6 +30,14 @@ class InlineEntityFormWebTest extends WebTestBase {
    * @var \Drupal\user\Entity\User
    */
   protected $user;
+
+  /**
+   * Field config storage.
+   *
+   * @var \Drupal\Core\Config\Entity\ConfigEntityStorage
+   */
+  protected $fieldStorageConfigStorage;
+
   /**
    * Prepares environment for
    */
@@ -41,6 +50,10 @@ class InlineEntityFormWebTest extends WebTestBase {
       'edit any ief_test_custom content',
       'view own unpublished content',
     ]);
+
+    $this->fieldStorageConfigStorage = $this->container
+      ->get('entity_type.manager')
+      ->getStorage('field_storage_config');
   }
 
   /**
@@ -65,17 +78,57 @@ class InlineEntityFormWebTest extends WebTestBase {
    * Tests simple IEF widget with single-value field.
    */
   public function testSimpleSingle() {
-    $this->drupalLogin($this->user);
-    $this->drupalGet('node/add/ief_simple_single');
+    $cardinality_options = [
+      1 => 1,
+      2 => 2,
+      FieldStorageDefinitionInterface::CARDINALITY_UNLIMITED => 1,
+    ];
+    foreach ($cardinality_options as $cardinality => $limit) {
+      /** @var \Drupal\field\FieldStorageConfigInterface $field_storage */
+      $field_storage = $this->fieldStorageConfigStorage->load('node.single');
+      $field_storage->setCardinality($cardinality);
+      $field_storage->save();
 
-    $this->assertText('Single node', 'Inline entity field widget title found.');
-    $this->assertText('Reference a single node.', 'Inline entity field description found.');
+      $this->drupalLogin($this->user);
+      $this->drupalGet('node/add/ief_simple_single');
 
-    $edit = [
-      'title[0][value]' => 'Host node',
-      'single[0][inline_entity_form][title][0][value]' => 'Child node',
-    ];
-    $this->drupalPostForm('node/add/ief_simple_single', $edit, t('Save'));
+      $this->assertText('Single node', 'Inline entity field widget title found.');
+      $this->assertText('Reference a single node.', 'Inline entity field description found.');
+
+      $edit = ['title[0][value]' => 'Host node'];
+      for ($item_number = 0; $item_number < $limit; $item_number++) {
+        $edit["single[$item_number][inline_entity_form][title][0][value]"] = 'Child node nr.' . $item_number;
+      }
+
+      $this->drupalPostForm('node/add/ief_simple_single', $edit, t('Save'));
+
+      for ($item_number = 0; $item_number < $limit; $item_number++) {
+        $this->assertText('Child node nr.' . $item_number, 'Label of referenced entity found.');
+      }
+    }
+  }
+
+  /**
+   * Gets IEF button name.
+   *
+   * @param array $xpath
+   *   Xpath of the button.
+   *
+   * @return string
+   *   The name of the button.
+   */
+  protected function getButtonName($xpath) {
+    $retval = '';
+    /** @var \SimpleXMLElement[] $elements */
+    if ($elements = $this->xpath($xpath)) {
+      foreach ($elements[0]->attributes() as $name => $value) {
+        if ($name == 'name') {
+          $retval = $value;
+          break;
+        }
+      }
+    }
+    return $retval;
   }
 
 }
diff --git a/tests/modules/inline_entity_form_test/config/install/core.entity_view_display.node.ief_simple_single.default.yml b/tests/modules/inline_entity_form_test/config/install/core.entity_view_display.node.ief_simple_single.default.yml
new file mode 100644
index 0000000..0b60ebf
--- /dev/null
+++ b/tests/modules/inline_entity_form_test/config/install/core.entity_view_display.node.ief_simple_single.default.yml
@@ -0,0 +1,22 @@
+langcode: en
+status: true
+dependencies:
+  config:
+    - field.field.node.ief_simple_single.single
+    - node.type.ief_simple_single
+  module:
+    - user
+id: node.ief_simple_single.default
+targetEntityType: node
+bundle: ief_simple_single
+mode: default
+content:
+  single:
+    type: entity_reference_label
+    weight: 0
+    label: above
+    settings:
+      link: false
+    third_party_settings: {  }
+hidden:
+  links: true
diff --git a/tests/modules/inline_entity_form_test/config/install/node.type.ief_test_custom.yml b/tests/modules/inline_entity_form_test/config/install/node.type.ief_test_custom.yml
index c1808a9..ccf0bc7 100644
--- a/tests/modules/inline_entity_form_test/config/install/node.type.ief_test_custom.yml
+++ b/tests/modules/inline_entity_form_test/config/install/node.type.ief_test_custom.yml
@@ -1,5 +1,5 @@
 type: ief_test_custom
-name: IEF test cestim
+name: IEF test custom
 description: 'Content type for IEF custom form testing.'
 help: ''
 new_revision: false