Firstly, I would recommend opening up a case with firstname.lastname@example.org
on this as they will be able to analyze your environment through support logs, etc.
Second, I would check the following:
1.) Are the vCenter, ESX Cluster, and ESX Hosts monitored by a nworks Collector? This can be checked from within the "Connected Servers" tab within the EMS Console.
2.) Check the health of your collectors by going to the _Enterprise Manager Dashboard within the [nworks VMware] views.
3.) Is the SCOM Agent functioning ok on each nworks Collector? Check out the "Agent Health State" dashboard within the view within the [Operations Manager\Agent] view. Make sure the "Agent State by Healthwatcher" is not having any issues.