WSO2 Identity server - SAML - redirection page keeps loading forever instead of taking me to the application

I am implementing the single sign on functionality using WSO2 identity server as the identity provider, PHP-SimpleSamlPhp package and Drupal following this article https://wso2.com/library/articles/2014/10/wso2-identity-server-single-sign-on-with-drupal/

Everything has been setup successfully as below.

1. Access the drupal app login page and click on the federated link
2. This redirects you to the WSO2 IS login page as expected
3. You enter the credentials (stored in WSO2) and click login
4. The page redirects you to the samlsso URL https://localhost:9443/samlsso?SAMLRequest=fZJNT....
5. This page keeps loading forever and the SAMLRequest value in the above URL keeps changing.

Logs

• This shows up at the point 2 above

TID: [-1234] [] [2020-04-12 18:48:14,334] [http://localhost/drupal-8.8.5/en/saml_login] INFO {org.opensaml.core.config.InitializationService} - Initializing OpenSAML using the Java Services API

• This shows up at point 5 above

TID: [-1234] [2020-04-12 18:53:06,793] [http://localhost/drupal-8.8.5/en/saml_login]  INFO {AUDIT_LOG} - Initiator=wso2.system.user Action=Get-User-List Target=null Data={"Claim Value":"ebdefe27-3912-4502-ad48-5b1a2ee30224","Users":["wickrema"],"Claim":"http://wso2.org/claims/userid"} Outcome=Success

TID: [-1234] [2020-04-12 18:53:06,793] [http://localhost/drupal-8.8.5/en/saml_login]  INFO {AUDIT_LOG} - Initiator=wso2.system.user Action=Get-User-Claim-Values Target=wickrema Data={"Claims":{"http://wso2.org/claims/username":"wickrema","http://wso2.org/claims/userid":"ebdefe27-3912-4502-ad48-5b1a2ee30224","http://wso2.org/claims/created":"2020-04-11T20:53:00.424Z","http://wso2.org/claims/role":"Internal/everyone","http://wso2.org/claims/fullname":"wickrema","http://wso2.org/claims/modified":"2020-04-11T20:53:33.922Z","http://wso2.org/claims/emailaddress":"wickrema@abc.com","http://wso2.org/claims/lastname":"Edirisooriya","http://wso2.org/claims/givenname":"Wickrema","http://wso2.org/claims/resourceType":"User","http://wso2.org/claims/userprincipal":"wickrema"}} Outcome=Success

TID: [-1234] [2020-04-12 18:53:06,794] [http://localhost/drupal-8.8.5/en/saml_login]  INFO {AUDIT_LOG} - Initiator : wickrema | Action : Login | Target : ApplicationAuthenticationFramework | Data : { "ContextIdentifier" : "4f08f619-e1dd-43be-8119-6cc7ea7238ee","AuthenticatedUser" : "wickrema","AuthenticatedUserTenantDomain" : "carbon.super","ServiceProviderName" : "simplesamlphp","RequestType" : "samlsso","RelyingParty" : "simplesaml","AuthenticatedIdPs" : "eyJ0eXAiOiJKV1QiLCAiYWxnIjoibm9uZSJ9.eyJpc3MiOiJ3c28yIiwiZXhwIjoxNTg2NzA2Nzg2NzcxMzAwMCwiaWF0IjoxNTg2NzA2Nzg2NzcxLCJpZHBzIjpbeyJpZHAiOiJMT0NBTCIsImF1dGhlbnRpY2F0b3IiOiJCYXNpY0F1dGhlbnRpY2F0b3IifV19." } | Result : Success 

Images

• More from the HTTP logs

0:0:0:0:0:0:0:1 - - [12/Apr/2020:20:04:20 +0300] GET /samlsso?SAMLRequest=fZJRT4MwEMe%2FCuk7a2EdyxpYMrcYl0wlG%2Frgi%2BlokSalxV5x%2Bu0FpnG%2B7KnN3f3%2B%2F7trU%2BCNbtmq87XZy%2FdOgg8%2BG22AjYkMdc4wy0EBM7yRwHzJDqv7HYsnhLXOeltajS6Q6wQHkM4ra1Cw3WTolc5oRZOjmJMpp1WViGRBovmUz%2BKSCCGiOJmRhSA0Iih4lg56MkO9UI8DdHJrwHPj%2BxCJSUhoGMVFNGeEspi8oGDTT6MM9yNVe98Cw1jbkuvagmcLSqd46BnAomD129raGuga6Q7SfahSPu13Z%2FiSxaCaVssBxo0VXX8dlTC04xmHvIRJW7f4BDYOoUVB%2FrOsG2WEMm%2FX93Q8FwG7K4o8zB8PBVqmgzAb53bLP%2F8UX8bT83s%2B9IrbTW61Kr%2BCW%2Bsa7q8bDhElwmosZd5xA0oa369Fa3taO8m9zJB3nUR4ebb8%2F2uW3w%3D%3D&RelayState=http%3A%2F%2Flocalhost%2Fdrupal-8.8.5%2Fen%2Fsaml_login HTTP/1.1 200 6020 - Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/80.0.3987.163 Safari/537.36 Edg/80.0.361.111 0.043

• Below is the authsources and identity provider configuration

• When I did a cookies check as suggested in the comments, this is what I found.

Adding answer as steps as requested

By design, domain names must have at least two dots; otherwise the browser will consider them invalid. (See reference on http://curl.haxx.se/rfc/cookie_spec.html)

When working on localhost, the cookie domain must be omitted entirely.

Modify the file /etc/hosts by adding the following entry

localhost.com 127.0.0.1

Then use the domain as localhost.com

For better cookie tracing in your browser, also follow the steps in the link https://brainshark.zendesk.com/hc/en-us/articles/205043644-Performing-a-Browser-Trace-Chrome