diff --git a/src/Plugin/search_api/processor/AddHierarchy.php b/src/Plugin/search_api/processor/AddHierarchy.php
index d338e97..77f1026 100644
--- a/src/Plugin/search_api/processor/AddHierarchy.php
+++ b/src/Plugin/search_api/processor/AddHierarchy.php
@@ -4,9 +4,9 @@
 
 use Drupal\Component\Utility\Html;
 use Drupal\Core\Entity\ContentEntityInterface;
+use Drupal\Core\Entity\EntityFieldManagerInterface;
 use Drupal\Core\Entity\EntityTypeManagerInterface;
 use Drupal\Core\Entity\TypedData\EntityDataDefinitionInterface;
-use Drupal\Core\Field\TypedData\FieldItemDataDefinition;
 use Drupal\Core\Form\FormStateInterface;
 use Drupal\Core\Plugin\PluginFormInterface;
 use Drupal\Core\TypedData\ComplexDataDefinitionInterface;
@@ -14,7 +14,6 @@
 use Drupal\search_api\Item\FieldInterface;
 use Drupal\search_api\Plugin\PluginFormTrait;
 use Drupal\search_api\Processor\ProcessorPluginBase;
-use Drupal\search_api\Utility\Utility;
 use Symfony\Component\DependencyInjection\ContainerInterface;
 
 /**
@@ -48,6 +47,13 @@ class AddHierarchy extends ProcessorPluginBase implements PluginFormInterface {
   protected $entityTypeManager;
 
   /**
+   * The entity field manager.
+   *
+   * @var \Drupal\Core\Entity\EntityFieldManagerInterface|null
+   */
+  protected $entityFieldManager;
+
+  /**
    * {@inheritdoc}
    */
   public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
@@ -83,6 +89,29 @@ public function setEntityTypeManager(EntityTypeManagerInterface $entity_type_man
   }
 
   /**
+   * Retrieves the entity field manager.
+   *
+   * @return \Drupal\Core\Entity\EntityFieldManagerInterface
+   *   The entity field manager.
+   */
+  public function getEntityFieldManager() {
+    return $this->entityFieldManager ?: \Drupal::service('entity_field.manager');
+  }
+
+  /**
+   * Sets the entity field manager.
+   *
+   * @param \Drupal\Core\Entity\EntityFieldManagerInterface $entity_field_manager
+   *   The new entity field manager.
+   *
+   * @return $this
+   */
+  public function setEntityFieldManager(EntityFieldManagerInterface $entity_field_manager) {
+    $this->entityFieldManager = $entity_field_manager;
+    return $this;
+  }
+
+  /**
    * {@inheritdoc}
    */
   public static function supportsIndex(IndexInterface $index) {
@@ -115,11 +144,23 @@ protected function getHierarchyFields() {
           $properties = $definition->getPropertyDefinitions();
           // The property might be an entity data definition itself.
           $properties[''] = $definition;
+          // Unfortunately, Core fails to correctly pass down an entity
+          // reference field's configured bundles to its "entity" sub-property,
+          // which means that only references that are base fields would be
+          // found. We therefore have to manually include the appropriate
+          // bundles in our code.
+          $bundles = array();
+          if ($definition->getDataType() === 'field_item:entity_reference') {
+            $settings = $definition->getSettings();
+            if (!empty($settings['handler_settings']['target_bundles'])) {
+              $bundles = $settings['handler_settings']['target_bundles'];
+            }
+          }
           foreach ($properties as $property) {
             $property_label = $property->getLabel();
             $property = $this->getFieldsHelper()->getInnerProperty($property);
             if ($property instanceof EntityDataDefinitionInterface) {
-              $options = self::findHierarchicalProperties($property, $property_label);
+              $options = self::findHierarchicalProperties($property, $property_label, $bundles);
               if ($options) {
                 $field_options += array($field_id => array());
                 $field_options[$field_id] += $options;
@@ -142,20 +183,30 @@ protected function getHierarchyFields() {
    *   The property to be searched for hierarchical nested properties.
    * @param string $property_label
    *   The property's label.
+   * @param string[] $bundles
+   *   (optional) Specific bundles to check for references, too.
    *
    * @return string[]
    *   An options list of hierarchical properties, keyed by the parent
    *   property's entity type ID and the nested properties identifier,
    *   concatenated with a dash (-).
    */
-  protected function findHierarchicalProperties(EntityDataDefinitionInterface $property, $property_label) {
+  protected function findHierarchicalProperties(EntityDataDefinitionInterface $property, $property_label, array $bundles = array()) {
     $entity_type_id = $property->getEntityTypeId();
     $options = array();
 
+    // Get the contained sub-properties of the property, as well as the
+    // properties on all the specified bundles.
+    $properties = $property->getPropertyDefinitions();
+    foreach ($bundles as $bundle) {
+      $properties += $this->getEntityFieldManager()
+        ->getFieldDefinitions($entity_type_id, $bundle);
+    }
+
     // Check properties for potential hierarchy. Check two levels down, since
     // Core's entity references all have an additional "entity" sub-property for
     // accessing the actual entity reference, which we'd otherwise miss.
-    foreach ($property->getPropertyDefinitions() as $name_2 => $property_2) {
+    foreach ($properties as $name_2 => $property_2) {
       $property_2_label = $property_2->getLabel();
       $property_2 = $this->getFieldsHelper()->getInnerProperty($property_2);
       if ($property_2 instanceof EntityDataDefinitionInterface) {
@@ -175,6 +226,7 @@ protected function findHierarchicalProperties(EntityDataDefinitionInterface $pro
         }
       }
     }
+
     return $options;
   }