#3351930: Drupal behaviors not running when element is shown

Closes #3351930

js/conditional_fields.js

@@ -195,6 +195,13 @@
             }
             e.effect = effect;
             originalHandler(e);
+
+            // Ensure Drupal behaviors get attached to visible fields only once.
+            if (e.type === 'state:visible') {
+              once('conditional-fields', e.target).forEach(() => {
+                Drupal.attachBehaviors(e.target);
+              });
+            }
           };
         }
       });