Chat SDK v2 Android - unable to send message

I want to use only the chat provider to send message to Zendesk. I have followed all the integration docs, and we are able to connect to socket, but whenever I try to send a message, it is getting added to queue but it is never sent.

What I found was that when I use the UI to send a message, all those message in queue is sent, and the queue is cleared only when I send a message through UI.

I integrated old version, Zopim SDK for Android and I was successfully able to send message using just the APIs.