200 sample response not showing in endpoint

I have a swagger 2.0 definition, which seems to get transformed to openapi 3 in readme. Within this definition, some endpoints show the 200 sample response at the right hand side of the page (below the call console), and some others don't show any sample response. I compared the paths between endpoints and they seem to be equal. The only difference between these endpoints is that one path/response points to a schema with required params, while the other pointed schema doesn't have required params (although, if I change that it doesn't seem to have an effect).

Here is a definition for checking: https://flex-trial.readme.io/openapi/617b34c5fa41cb078f0f4bf1

This endpoint doesn't have sample response: https://flex-trial.readme.io/v2.0/reference/getconversations

This one does: https://flex-trial.readme.io/v2.0/reference/getcontacts

Is there any clue on why readme is not picking up the responses?