Apigee integrated portal not calling Single logout URL SAML IDP when clicking Signout

I am trying to Configure single sign on in Apigee Dev portal using Custom IDP. I am able to login using the SSO using our custom IDP provider, but while log out its not clearing the credentials from the browser. The cookies are getting clear on clicking sign out from the integrated portal but the SAML login credentials are getting cached.

While clicking on sign out from the portal its not calling or redirected to below mentioned Sign-out URL.

So when i am clicking on signin again after sign out the screen is not asking for SSO credentials again and its continuing with already cached credentials.

Steps i have done to configure SSO in integrated dev portal

1. Below is the configuration where i have mentioned the SSO and SLO provided by my IDP.

2. Also added the certificated in the configuration provided by IDP.

I want Apigee integrated portal to call IDP SLO which is configured in SAML settings when i click on the sign out in apigee integrated portal

Note: When i closing the browser the Single Sign on screen . is coming after logout and login.