We noticed that NetXMS has been using the following path as the state directory for cca. 4-5 last minor versions:
org.netxms.nxmc.Startup - State directory: /var/lib/tomcat*/null/state
What's with the "/null/"?
Since this path doesn't exist by default, session settings customizations don't persist until the directory structure is manually created and rw permissions are configured for the tomcat user.