diff --git a/includes/type/enum/class-product-attribute-enum.php b/includes/type/enum/class-product-attribute-enum.php
index a5313562..db30fdef 100644
--- a/includes/type/enum/class-product-attribute-enum.php
+++ b/includes/type/enum/class-product-attribute-enum.php
@@ -32,6 +32,10 @@ public static function register() {
 			}
 		}
 
+		if ( empty( $taxonomy_values ) ) {
+			$taxonomy_values['NONE'] = [ 'value' => 'none' ];
+		}
+
 		register_graphql_enum_type(
 			'ProductAttributeEnum',
 			[