Today Google updated Hangout 8.0 with new features. Update brings Android N support to the Hangout App. In Android N features, it supports Notification bundles and Quick Reply as well.
Hangout App now supports quick reply and Notification bundles. So you can now quickly reply from Notification toggle to your messages.
When you update to hangout 8.0, many issues are completely solved. Direct Reply also working inside Notification center.
So have you updated Hangout app? Comments below.