This is most of the time caused by notification settings for a browser or an app. So, first, double-check that notifications are allowed in your browser/app as well as in your device settings. Also, you can try clearing cache and cookies, logging out and back in, or seeing if Blackboard is configured to send announcements and course updates. In case the problem persists, it is most likely that it will be resolved by updating the app or by getting in touch with Sullivan IT support.