redux-persist: redux-persist is not working

I followed doc here for setup --> https://github.com/rt2zz/redux-persist

Basically I’ve simple basic setup as per the document

import { createStore } from 'redux'
import { persistStore, persistReducer } from 'redux-persist'
import storage from 'redux-persist/lib/storage'
import user from './reducers/user';

const persistConfig = {
  key: 'root',
  storage,
}

const rootReducer = combineReducers({user: user});

const persistedReducer = persistReducer(persistConfig, rootReducer);

const store = createStore(persistedReducer, applyMiddleware(thunk));

const persistor = persistStore(store);

export { store, persistor } ;

And then, I add PersistGate in my render.

ReactDOM.render(
  <Provider store={store}>
    <PersistGate loading={null} persistor={persistor} >
      <RootRouter />
    </PersistGate>
  </Provider> ,
  document.getElementById('root')
);

But still when I refresh my page, it doesn’t keep those states active. The only difference I can see in my code (than document) is that I’m using thunk. Can someone please help me?