@Lionel Thanks for the feedback. Other users are reporting that notifications don't work after upgrading to iOS 8.
Currently, the only solution is to uninstall Cyphr and reinstall the app. Unfortunately, all your conversations will deleted when you uninstall Cyphr.
We are working on multi-device mode, so your conservations can be restored from our servers . We are still in early testing of multi-device functionality so the release is weeks away.
Thanks again for the feedback!