All of HubSpot's certification tests are timed, and the timer starts as soon as you view the first page of questions.
If you received a notification that you did not pass a certification test when you did not take it, it is likely that you started the test at a previous time, but closed out of it before finishing.
The test timer keeps running whether you still have the test window open or not, and the system can't send notifications of expired time while you're not logged in. As a result, you'll receive notification of not passing the exam when you return to the page. The test will unlock itself 24 hours after you receive this notification.