And there also no entries in 'View - Evenlog' ('Syslog Monitor' is only the live view)?
Is syslog activated in Server Configuration? (EnableSyslogDaemon = 1)
Check also what you have in the Server Configuration Value 'SyslogNodeMatchingPolicy', default is '0', so the NetXMS syslog server tries first matching incoming syslog-messages by source IP address (check that incoming messages come from primary IP address of this node in NetXMS) and than by 'Host Name' field in the syslog-message itself.
Maybe that helps finding the cause.
