What sensor model /software version is this an issue on?
I had an issue with some of my NS sensors last year where the firewall rules stopped working and they didn't generate any syslog notifications. It was a software bug # 1082660 and was fixed in the 184.108.40.206 software release.
Thanks for responding. It turns out it was just a matter of being patient it seems. For some reason it took quite some time for the ogs to go into ArcSight initially, but once they began showing up the the firewall rules I was testing started to populate within a minute or two after triggering.