Hello &7 Welcome @Roleta
To help you further we would need more information on how you are ingesting XigmaNAS logs.
What you posted could be multiple reasons why your have that issue.
For better clarity please look here.
EDIT:
Newer set of RFCs for syslog called the IETF Syslog Protocol (RFCs 5424-5426) that defined a syslog standard meant to obsolete RFC 3164.