insert during executing FGAC (dbms_rls package)

Hello.
Please, look at my example where I use FGAC dbms_rls.add_policy

as user SCOTT:

CREATE TABLE test_table (
  a NUMBER(10,0) NULL
)
/

CREATE OR REPLACE function policy_test_table (object_schema IN VARCHAR2, object_name VARCHAR2) RETURN VARCHAR2 IS
BEGIN
 INSERT INTO test_table VALUES (99);
 RETURN '';                       
END;
/

and a test query to check this does work

SELECT * FROM test_table;

as user SYS:

BEGIN
 DBMS_RLS.ADD_POLICY (
 object_schema => 'scott',
 object_name => 'test_table',
 policy_name => 'test_table_policy',
 function_schema => 'scott',
 policy_function => 'policy_test_table',
 statement_types => 'SELECT',
 update_check => TRUE,
 enable => TRUE,
 static_policy => FALSE);