Ping Federate: Error while getting Access Token - pingfederate

Question

I am trying to retrieve 'Access Token' using 'Authorisation Code' grant type using Ping Federate.
Ping federate is configured with
Callback URL,
Auth URL,
Access Token URL,
Client ID and Client Secret
Scope: openid

But when i try to request for Access token using Postman 'Get Access Token' feature, i am getting below error.
"The global default access token manager is not available for the selected client and authentication context"
I have configured Access token manager to the client.
Anybody have come across such error and would appreciate if you could help with this.
PingFederate Logs:
entityId: devenuat (null)
virtualServerId: null
Binding: oauth:authz
relayState:
params: {code=IVFUPjrUIMYVP8Djti9Bkwz3gLDbygS5_nMAAAAC, state=}
Endpoint: http://ec2-34-255-9-65.eu-west-1.compute.amazonaws.com:8080/authentication/login?code=IVFUPjrUIMYVP8Djti9Bkwz3gLDbygS5_nMAAAAC&state= <http://ec2-34-255-9-65.eu-west-1.compute.amazonaws.com:8080/authentication/login?code=IVFUPjrUIMYVP8Djti9Bkwz3gLDbygS5_nMAAAAC&state=>
SignaturePolicy: BINDING_DEFAULT
2019-11-29 11:20:35,305 DEBUG [org.sourceid.servlet.HttpServletRespProxy] adding lazy cookie Cookie{PF=hashedValue:26e1qHIcgNhYfWhMIqK35xMF_mU; path=/; maxAge=-1; domain=null} replacing null
2019-11-29 11:20:35,305 tid:26e1qHIcgNhYfWhMIqK35xMF_mU DEBUG [org.sourceid.websso.servlet.ProtocolControllerServlet] ---REQUEST (POST)/as/token.oauth2 from 92.123.73.225:
---PARAMETERS---
code:
IVFUPjrUIMYVP8Djti9Bkwz3gLDbygS5_nMAAAAC
grant_type:
authorization_code
redirect_uri:
http://ec2-34-255-9-65.eu-west-1.compute.amazonaws.com:8080/authentication/login <http://ec2-34-255-9-65.eu-west-1.compute.amazonaws.com:8080/authentication/login>
client_id:
devenuat