diff --git a/core/modules/block/src/BlockForm.php b/core/modules/block/src/BlockForm.php
index 605cf40..609c2d6 100644
--- a/core/modules/block/src/BlockForm.php
+++ b/core/modules/block/src/BlockForm.php
@@ -352,7 +352,7 @@ public function submitForm(array &$form, FormStateInterface $form_state) {
         ->setValues($values);
       $condition->submitConfigurationForm($form, $condition_values);
       if ($condition instanceof ContextAwarePluginInterface && $condition->getContextDefinitions()) {
-        $context_mapping = isset($values['context_mapping']) ? $values['context_mapping'] : [];
+        $context_mapping = $condition_values->getValue('context_mapping', []);
         $condition->setContextMapping($context_mapping);
       }
       // Update the original form values.
@@ -362,7 +362,7 @@ public function submitForm(array &$form, FormStateInterface $form_state) {
       $entity->getVisibilityConditions()->addInstanceId($condition_id, $condition_configuration);
     }
 
-    // Save the settings of the plugin.
+    // Save the updated block.
     $entity->save();
 
     drupal_set_message($this->t('The block configuration has been saved.'));