diff --git a/src/Bundle/ChillActivityBundle/Entity/ActivityType.php b/src/Bundle/ChillActivityBundle/Entity/ActivityType.php
index ec1012136..f8e871942 100644
--- a/src/Bundle/ChillActivityBundle/Entity/ActivityType.php
+++ b/src/Bundle/ChillActivityBundle/Entity/ActivityType.php
@@ -11,7 +11,6 @@ declare(strict_types=1);
 
 namespace Chill\ActivityBundle\Entity;
 
-use Doctrine\Common\Util\ClassUtils;
 use Doctrine\ORM\Mapping as ORM;
 use Symfony\Component\Serializer\Annotation as Serializer;
 use Symfony\Component\Serializer\Annotation\Groups;
@@ -463,7 +462,11 @@ class ActivityType
         $property = $field.'Visible';
 
         // Get the real class name (not the proxy)
-        $realClass = ClassUtils::getClass($this);
+        $class = get_class($this);
+        if (str_contains($class, '__CG__')) {
+            $class = get_parent_class($this);
+        }
+        $realClass = $class;
 
         if (!property_exists($realClass, $property)) {
             throw new \InvalidArgumentException('Field "'.$field.'" not found');