firewall policy seems OK, so any other cause like resticted network or SNMP community mismatch may prevent SNMP poling access. Capturing packets on both SNMP manager host and cluster management LIF node may help to isolete the problem.
the same alert we received today. we are using Netapp 7 mode and we have limited commands or option in GUI to check the logs as mentioned in this topic. Did you resolved after checking with SNMP manager admin? what was the action taken for this alert?