There are three reasons why audit events for all your vCenter Servers are not displayed. Follow the troubleshooting steps if you do not see audit events from all the vCenter Servers in your infrastructure.

Reason 1: vCenter Servers are registered with VMware Aria Operations but not with VMware Aria Operations for Logs.
Solution: You must configure VMware Aria Operations for Logs to work with vCenter Server instances by performing the steps in the topic, Configure VMware Aria Operations for Logs to Pull Events, Tasks, and Alarms from vCenter Server Instance.
Reason 2: VMware Aria Operations for Logs Log Forwarding instances are not of the required version.
Solution: All versions of VMware Aria Operations for Logs must be of the 8.18+ version. You can perform the upgrade by following the steps in the topic, Upgrading VMware Aria Operations for Logs.
Reason 3: Bidirectional sync between VMware Aria Operations for Logs and VMware Aria Operations has failed.
Solution: You must configure the VMware Aria Operations for Logs management pack from the Administration > Integrations page in VMware Aria Operations. This ensures bidirectional sync. For more information, see the topic, Configuring VMware Aria Operations for Logs with VMware Aria Operations