For anyone else having this issue in Postman (which does automatically handle cookies by default), make sure you are using an HTTPS:// URI. If you copied/pasted from API Inspector in the APIC, it uses HTTP which only works from within the interface. ...

I don't think there is a way to pull existing data out in any format for import into another tool. You will have to just use FMC for analysis of the existing data, and start sending syslog data to the SIEM from this point forward.Ryan