I would suggest to try the latest binding which has better support for the notification class -:
https://community.openhab.org/t/oh2-z-wave-refactoring-and-testing-and-security
Note that this needs to be manually installed (see the first few messages in the thread) and it will need the 2.4 snapshot (or at least 2.3 stable) to run.
If you have problems, then post the debug logs and the XML file generated and I’ll take a look.