On a gateway that is logging locally, what IP address is the gateway trying to reach for sending logs? Run netstat -an | grep :257 to to check this. If it is still trying to send to the old IP address and policy has already been reinstalled, you'll probably need to kill the fwd daemon and let it restart. Note that doing so will cause a failover in a HA environment and may cause brief traffic issues. I've seen many situations where fwd refuses to let go of an old logging address, even though policy has been reinstalled with the new one set and restarting fwd is the only way to fix it.
If it is sending to the right NAT address you have some other connectivity issue, probably at the intervening gateway that is actually performing the NAT operation for the logging port 257 traffic.
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