External logout not working from the navigation dashboard

I’m a newbie in icinga2. We’re trying to set up the icingaweb2 to have an SSO authentication using the mod_auth_openidc module with pingID as IDP. Although we have a successful login, however, once we logged out we have this kind of message.
“Logging out…
If this message does not disappear, it might be necessary to quit the current session manually by clearing the cache, or by closing the current browser session.”

Icinga Web 2 Version 2.11.0
PHP Version 7.4.6