No Active Transaction after using datamanager and using a function with @Transactional

Support
#1

Hello. I’m a bit confused on whats happening here.
I load an entity using the datamanager but cant execute the next function with the @Transactional annotation. Thank you for the help explaining this odd behaviour.

 @Override
public void testTx() {
    User user = dataManager.load(User.class).query("SELECT u from sec$User u where u.login = 'admin'").one();
    System.out.println("user = " + user);
    //NO ACTIVE TRANSACTION
    simpleFun();
}

@Transactional
void simpleFun(){
    logTxId();
}

private void logTxId() {
    String firstResult = (String) persistence.getEntityManager()
            .createNativeQuery("SELECT CAST(txid_current() AS text)").getFirstResult();
    System.out.println(firstResult);
}