Missing refresh token in respose (Zoho-CRM V2 API)

Missing refresh token in respose (Zoho-CRM V2 API)

I am facing an issue in which I don't get any refresh token. You can reproduce it as-
1. Create a developer app in https://accounts.zoho.com/developerconsole
2. Use generated client id and client secret and after entering username, password click on the accept button to get the 'code'.
3. Use code to generate access token and refresh token. This time you will get response as 
"{
"access_token": "{access_token}",
"refresh_token": "{refresh_token}",
"expires_in_sec": 3600,
"api_domain": "https://www.zohoapis.com",
"token_type": "Bearer",
"expires_in": 3600000
}"
4. Now use exactly the same client id, client secret, and same login account and repeat step 2 and 3. This time you will get response as 
"{"access_token":"{access_token}",
"expires_in_sec":3600,
"api_domain":"https://www.zohoapis.com",
"token_type":"Bearer",
"expires_in":3600000
}"
You can see refresh token is missing in the above response. It looks like a bug. Please fix it..