Monitoring of ESXi on vCenter was possible with Zabbix 2.2, but with 4.0 it is no longer possible.
Upon investigation it was found that in this environment there are duplicate Hardware UUIDs for ESXi deployed on vCenter.

A quick internet search revealed that some manufacturers have devices with duplicate hardware UUIDs.
Even in 4.0, if you move the guest OS to an ESXi with a non-overlapping HW_UUID, you will be able to monitor it.
As we were able to monitor with the same settings in 2.2, we would like to monitor with duplicate HW UUIDs in 4.0.

HV_UUID: 03000200-0400-0500-0006-000700080009
UUID: UNIQUE

Confirmed Item Keys

• vmware.vm.cpu.num[\{$URL}, \{$UUID}]
• vmware.vm.cpu.num[\{$URL}, \{$HV_UUID}]