diff -u b/core/lib/Drupal/Core/Entity/ContentEntityBase.php b/core/lib/Drupal/Core/Entity/ContentEntityBase.php
--- b/core/lib/Drupal/Core/Entity/ContentEntityBase.php
+++ b/core/lib/Drupal/Core/Entity/ContentEntityBase.php
@@ -1094,7 +1094,8 @@
 
     // Ensure that the following properties are actually cloned by
     // overwriting the original references with ones pointing to copies of
-    // them: enforceIsNew, newRevision, loadedRevisionId, fields and entityKeys.
+    // them: enforceIsNew, newRevision, loadedRevisionId, fields, entityKeys and
+    // translatableEntityKeys.
     $enforce_is_new = $this->enforceIsNew;
     $this->enforceIsNew = &$enforce_is_new;
 
@@ -1110,6 +1111,9 @@
     $entity_keys = $this->entityKeys;
     $this->entityKeys = &$entity_keys;
 
+    $translatable_entity_keys = $this->translatableEntityKeys;
+    $this->translatableEntityKeys = &$translatable_entity_keys;
+
     foreach ($this->fields as $name => $values) {
       $this->fields[$name] = [];
       // Untranslatable fields may have multiple references for the same field