@Balarama Krishnayya

The container configuration has a setting to have impressions automatically captured at decision time or to have the channel capture the impression.  The default was changed to have the channel capture the impression as that is the documented best practice.  This is a best practice as its bad to assume that just because a decision was made, that a customer would view that action.  The channel is much better placed to understand when a customer was actually served up an action and that the customer was actually shown it (impression).  This obviously also helps the system better learn about what is really happening with customer engagement, rather than creating false perceptions of impression that potentially never happened.