Twitch webhook subscription gets created successfully but my server is not receiving updates

API
3

Yes I am using NGROK and yes it was tunneling, I can say that because I sent a dummy POST request on the https://<ngrok_url>/twitch/callback and I saw that request getting handled by my web server.

I will test it with some big twitch streamer and let you know.

My entire flow.
step 1. sending request to twitch to for subscribing.

await request({
    url: API_BASE_URL + '/webhooks/hub',
    method: 'POST',
    headers: {
        'Client-ID': this.config.clientId,
        'Content-Type': 'application/json'
    },
    form: {
        'hub.callback': https://<ngrok_url>/twitch/webhook?item.id=<random_string_a>',
        'hub.mode': 'subscribe',
        'hub.topic': 'https://api.twitch.tv/helix/users/follows?first=1&to_id=<twitch_channel_id>',
        'hub.lease_seconds': 864000,
        'hub.secret': <random_string_b>
    },
    json: true
});

step 2. Setting up webhooks in express so that it will accept requests coming from twitch.

router.get('/twitch/webhook', (req, res) => {
    // confirms subscription

	res.status(200).send(<challenge_string>);
});

router.post('/twitch/webhook', (req, res) => {
    // my business logic

	res.send(200);
});

step 3. I am getting getting GET /twitch/webhook, and once I send the <challenge_string> that I get from query string itself then I see a new entry when I fetch list of my active subscriptions from twitch.

step 4. Whenever I follow or unfollow the channel that has it’s id set to <twitch_channel_id> my web server should receive POST request from twitch with relevant data (which is not happening right now).