i suggest a MoM HA snmp action enhancement because up to the current APM version (10.2) the snmp actions for alerts are not sent if the primary fails and the secondary takes it's role.
as if we create SNMP action for any alert, we need to fill in the source IP address (so we choose the primary MoM's IP address in case of APM MoM HA).
in case the primary MoM fails and secondary MoM takes it's role, then the alerts are not sent as the IP address in the action is not valid (it's the manually configured primary MoM's IP address instead of the currently used secondary MoM's IP address).
so the MoM HA mode is not fulfilled.
the issue is described in apm mom snmp trap - ha