We are developing a paid app, Freshsales - Sage integration. In that integration we are using account level Oauth to authenticate Sage. (I've attached the sage documentation for your reference)

Please find Sage document here

When the app is authenticated for the first time, the refresh token and access token is getting generated and the sage APIs are working. But after the expiration period of the access token, the refresh token flow is not happening. We couldn't be able to check whether the refresh token is getting stored in the app storage since we weren't able to run the app locally. 

Could you please help us with this? In the postman, we were able to see that refresh token also getting returned along with the access token. 

I've attached the file that we are using (oauth_config.json)