Memcached – Session Data is not updating

I m using express-session and memcached-connect package for maintaining session.
Everything is working as expected.

Here is my implementation:

Middleware

app.use(session({
    rolling: true,
    secret: 'iloveexpress',
    proxy: 'true',
    store: new MemcachedStore({
        hosts: ['127.0.0.1:11211']
    }),
    cookie: {
        maxAge: 86400000,
        path: "/",
        domain: 'example.com'
    }, //1 Day
    saveUninitialized: false,
    resave: true
}));

Setting Session

req.session.data = {
   id: '123,
   name: 'ABC',
   amount: 1000,
   profilePic: '/images/asd.jpg'
}

Updating Session

req.session.data.amount = 500;

But when I update a particular data in the session, it not updating. The other time I make a request to the Api its showing the old data, i.e., amount = 1000;

EDIT:
console of req.session

Session {
  cookie:
   { path: '/',
     _expires: 2017-09-20T07:11:35.394Z,
     originalMaxAge: 86399951,
     httpOnly: true,
     domain: 'example.com' },
  data:
   { id: '591173362ad30b419e2c4f54',
     name: 'ABC',
     amount: 1000,
     profilePic: '/image/1496663576532Koala.jpg' } }