Thanks again for reporting this issue! Unfortunately we weren't able to reproduce this error, can you let us know what happens when you knock on your phone? Do you still get the "Knock knock knock" notification or does the notification not show up at all? To ensure that the Sesame app is ready for the knock command, we recommend knocking on your phone immediately after you receive the "Welcome back" notification or after you minimize the Sesame app.
If you are still unable to get knock to work, can you please provide us with a timestamp of when knock failed for you (please specify time zone) so we can check it out? Thanks so much! - CANDY HOUSE