There is a bug in the notification system. Whenever you show a notification then show another (or the same) notification while the first is still visible, when it's time for the first to close both of them will close at the same time. Even with different durations, this still happens. Should be easy to reproduce.
Same problem here.
I show 5 notifications in short time span.
a few of them closes correct.
others remains visible until closed via the close button
may have something to do with the amaount of notifications.
The more i show the more stays visible/open.