diff -u b/core/lib/Drupal/Core/Entity/EntityStorageBase.php b/core/lib/Drupal/Core/Entity/EntityStorageBase.php
--- b/core/lib/Drupal/Core/Entity/EntityStorageBase.php
+++ b/core/lib/Drupal/Core/Entity/EntityStorageBase.php
@@ -364,8 +364,12 @@
     $entities_by_class = $this->getEntitiesByClass($entities);
 
     // Invoke entity class specific postLoad() methods.
-    foreach ($entities_by_class as $entity_class => &$items) {
-      $entity_class::postLoad($this, $items);
+    foreach (array_keys($entities_by_class) as $entity_class) {
+      // We must pass the full $entities array each time, so that if a
+      // postLoad() method is trying to reorder the array (for example,
+      // \Drupal\user\Entity\Role::postLoad()), it can actually manipulate the
+      // final array, not a subarray.
+      $entity_class::postLoad($this, $entities);
     }
     // Call hook_entity_load().
     foreach ($this->moduleHandler()->getImplementations('entity_load') as $module) {
diff -u b/core/tests/Drupal/KernelTests/Core/Entity/BundleClassTest.php b/core/tests/Drupal/KernelTests/Core/Entity/BundleClassTest.php
--- b/core/tests/Drupal/KernelTests/Core/Entity/BundleClassTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Entity/BundleClassTest.php
@@ -146,11 +146,11 @@
     $this->assertEquals(2, EntityTestBundleClass::$postLoadCount);
     $this->assertCount(2, EntityTestBundleClass::$postLoadEntitiesCount);
 
-    // Only 3 of the 5 entities we just loaded use the bundle class. However,
-    // one of them has already been loaded and we're getting the cached entity
-    // without re-invoking postLoad(). So the custom postLoad() method should
-    // only have been invoked with 2 entities.
-    $this->assertEquals(2, EntityTestBundleClass::$postLoadEntitiesCount[1]);
+    // Only 4 of the 5 requested entities need to be loaded. The other ($entity)
+    // has already been loaded and we're getting the cached entity without
+    // re-invoking postLoad(). So the custom postLoad() method should only have
+    // been invoked with 4 entities.
+    $this->assertEquals(4, EntityTestBundleClass::$postLoadEntitiesCount[1]);
 
     // Reset the storage cache and try loading again.
     $this->storage->resetCache();
@@ -158,8 +158,8 @@
     $entities = $this->storage->loadMultiple($entity_ids);
     $this->assertEquals(3, EntityTestBundleClass::$postLoadCount);
     $this->assertCount(3, EntityTestBundleClass::$postLoadEntitiesCount);
-    // This time, all 3 bundle_class entities should be included.
-    $this->assertEquals(3, EntityTestBundleClass::$postLoadEntitiesCount[2]);
+    // This time, all 5 entities should be included.
+    $this->assertEquals(5, EntityTestBundleClass::$postLoadEntitiesCount[2]);
 
     // Start deleting things and count delete-related method invocations.
     $entity_test_1->delete();