Sid value is null in Automating Authorization Code Flow

Hello All,

I am successfully got the code and access token in the authorization code flow using PKCE, but in the HTTP header, the sid value is null, so not able to set cookies correctly.
set-cookie: sid=“”; Expires=Thu, 01-Jan-1970 00:00:10 GMT; Path=/, set-cookie: autolaunch_triggered=“”; Expires=Thu, 01-Jan-1970 00:00:10 GMT; Path=/, set-cookie: JSESSIONID=EAE2921F6F61778782CB6F88D7C4D041; Path=/; Secure; HttpOnly] ResponseEntityProxy{[Content-Type: application/json,Chunked: true]}}

Can anyone tell us what are the reasons for it? I am not using any browser flow for the authenticationa and authorization .