The path to Audit are changed in Zabbix 3.0
The documentation about actions need to be updated
https://www.zabbix.com/documentation/3.0/manual/config/notifications/action/operation/message

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In //Administration -> Audit//, if you select //Actions// from the dropdown, you will see details of all actions taken for those events that have an action configured.

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I think the Audit dont have more the message information... this now is on action log.