I am able to replicate this but this is not a bug its normal behaviour of the app.
The reason why its behaving like this is
a) oxAuth session ( login session ) is being created when you initiate SSO session from RP ( app )
b) In general case, if session is expired and user hit login.. it would go to RP page and say… “session expired, please re-login”
c) On this case , our RP is ‘oxTrust’ itself
So that when you removed cache or cookies session interupted and need to created again by refresh oxtrust login page.
For any further issues , please feel to reach gluu support.
Thanks and Regards