Hard to tell without a complete ZW debug log during the time in question. Also what is the ZW network size. Since I’d say it is not normal, might want to review this posting. [SOLVED] Unresponsive Z-Wave Network: Tools and Approaches to track down the issues - Tutorials & Examples / Solutions - openHAB Community
One guess is the controller to device communication is not good. Could have some zombie nodes that are interfering, etc. Only blind advice is to check karaf for orphan links and purge them