Please note that IRCTC doing changes in the Passenger Details page. Autofills are not working on this page. As on 4th Dec, 2017 it is logging you out.

So please type all the details manually. Don't use copy paste.

Please practice with Aam Aadmi Tatkal once with these settings turned on(as in photo below) .

There is good chance that Aam Aadmi with work with the setting.

Also keep ready browser without any extension.

Firefox Version | Google Chrome Version. | Aam Aadmi Version History