diff -u b/core/includes/config.inc b/core/includes/config.inc
--- b/core/includes/config.inc
+++ b/core/includes/config.inc
@@ -141,11 +141,11 @@
     'delete' => array(),
   );
 
-  foreach (array_diff_assoc($target_config_data, $source_config_data) as $name => $value) {
+  foreach (array_diff_key($target_config_data, $source_config_data) as $name => $value) {
     $config_changes['delete'][] = $value['name'];
   }
 
-  foreach (array_diff_assoc($source_config_data, $target_config_data) as $name => $value) {
+  foreach (array_diff_key($source_config_data, $target_config_data) as $name => $value) {
     $config_changes['create'][] = $value['name'];
   }
 
@@ -200,6 +200,8 @@
  *   synchronization error, or NULL if there are no changes to synchronize.
  */
 function config_import() {
+  // Invalidate config objects.
+  drupal_container()->get('config.factory')->resetConfigs();
   // Retrieve a list of differences between staging and the active configuration.
   $source_storage = drupal_container()->get('config.storage.staging');
   $target_storage = drupal_container()->get('config.storage');
diff -u b/core/lib/Drupal/Core/Config/Config.php b/core/lib/Drupal/Core/Config/Config.php
--- b/core/lib/Drupal/Core/Config/Config.php
+++ b/core/lib/Drupal/Core/Config/Config.php
@@ -127,6 +127,9 @@
    *   TRUE if this config object does not exist in storage.
    */
   public function isNew() {
+    if (!$this->isLoaded) {
+      $this->load();
+    }
     return $this->isNew;
   }
 
diff -u b/core/lib/Drupal/Core/Config/ConfigFactory.php b/core/lib/Drupal/Core/Config/ConfigFactory.php
--- b/core/lib/Drupal/Core/Config/ConfigFactory.php
+++ b/core/lib/Drupal/Core/Config/ConfigFactory.php
@@ -79,2 +79,5 @@
 
+  function resetConfigs() {
+    $this->configs = array();
+  }
 }