Update to Drupal 8.0.6. For more information, see https://www.drupal.org/drupal-8.0.6-release-notes

core/misc/autocomplete.js

@@ -200,8 +200,9 @@
         });
         // Use jQuery UI Autocomplete on the textfield.
         $autocomplete.autocomplete(autocomplete.options)
-          .data('ui-autocomplete')
-          ._renderItem = autocomplete.options.renderItem;
+          .each(function() {
+            $(this).data('ui-autocomplete')._renderItem = autocomplete.options.renderItem;
+          });
       }
     },
     detach: function (context, settings, trigger) {