diff -u b/src/Form/EntityEmbedDialog.php b/src/Form/EntityEmbedDialog.php
--- b/src/Form/EntityEmbedDialog.php
+++ b/src/Form/EntityEmbedDialog.php
@@ -566,6 +566,23 @@
         '#value' => $entity_element['data-entity-uuid'],
       );
 
+      // TODO: Also set data-entity-embed-display-settings.
+      $form['attributes']['data-entity-embed-display'] = array(
+        '#type' => 'hidden',
+        '#default_value' => $entity_element['data-entity-embed-display'],
+        '#required' => TRUE,
+      );
+      $form['attributes']['data-align'] = array(
+        '#type' => 'hidden',
+        '#default_value' => isset($entity_element['data-align']) ? $entity_element['data-align'] : '',
+      );
+      $form['attributes']['data-caption'] = array(
+        '#type' => 'hidden',
+        '#default_value' => isset($entity_element['data-caption']) ? Html::decodeEntities($entity_element['data-caption']) : '',
+        '#element_validate' => array('::escapeValue'),
+      );
+
+
       $form['actions'] = array(
         '#type' => 'actions',
       );