CI 4.3.5 - Session Expiration Not Working

I was too thinking something like that , but again that is something we need to build by self and its not feature of CI4.
i was just testing with

expiration 7200 (2 hours)  Time in seconds (integer)

and found this is also not working , i am sure their is some issue with this version , because early in 4.1.1 it was working fine with 2 hours atleast.

if possible you please inform your team.
Thanks