run from the terminal and see if you get something similar or close to this bug: https://bugs.launchpad.net/nonotifs/+bug/1636740
In any case, I generally don't advise notification managers of any kind, except if provided by a) the distro maintainers or b) an upstream project that is already managing the notification system and decides to expose it to the user, like a DE for instance. These are the only two I know that work. Anything else is always a constant headache of bugs and annoyances, that can be easily avoided by instead resorting to a per-application configuration (unfortunately not every application that uses notifications includes settings to manage them).
So, I would say, forget about
nonotify. I don't know of one single notification tool that works on linux. Not a one!
I don't know who to blame. If the
libnotify developers, or the developers of these tools. But what I know is that the only ones I trust to do a good job on this area are those I already mentioned: Distro maintainers or DE developers. And I won't use anything from anyone else. The before mentioned Xfce feature tool is an excellent example of why this is so. It just works. And it works continuously without problems, that you just forget all about it.