The physical navigator shows some agents using the fully qualified domain name (FQDN).
In the agent node, the variables CTIRA_HOSTNAME and CTIRA_SYSTEM_NAME are set to the short hostname and the /etc/host is also set correctly.
Resolving the problem
The problem occurs on systems where also very old Agent Builder agents (EG older than 6.2.2) are installed and running.It depends on the agent infrastructure layer used by the custom agent.
Rebuilding the custom agent with a newer Agent Builder version and upgrading it in the failing nodes helps solving the problem.