diff --git a/lib/api/v3/work_packages/schema/work_package_schema_representer.rb b/lib/api/v3/work_packages/schema/work_package_schema_representer.rb
index 0f6935096c..fa5e3e68f4 100644
--- a/lib/api/v3/work_packages/schema/work_package_schema_representer.rb
+++ b/lib/api/v3/work_packages/schema/work_package_schema_representer.rb
@@ -304,6 +304,7 @@ module API
           def form_config_attribute_representation(group)
             cache_keys = ['wp_schema_attribute_group',
                           group.key,
+                          group.attributes,
                           I18n.locale,
                           represented.project,
                           represented.type,