We have noticed that Opmanager is not keeping track of VMs properly. We recently upgraded to ESX 5.5 but it may of been happening before.
If you drill down into one of the ESX hosts, the number of VMs at the top right is correct, but the listed VMs on the server are not correct and number of VMs does not match the top figure.
This is happening on all the ESX servers we are monitoring. We are running the latest version of Opmanager.