I created a new system name for the clustered nodes, and so I deleted old system name in AES. The Current System dropdown list does not seem to be repopulated again after the deletion? Same with the Enterprise Heath landing page, I used to see a system with 2/2 nodes, but after I deleted the system, I don't see the row anymore?
However Exceptions and Alerts seem to be coming into AES without a problem.
I have also restarted both AES and the monitored nodes, but still AES does not show the system.
I think I used the IP 10.0.0.5 listed at the time (ipconfig) instead of hostname and when the AES restart it has a new IP. So I change the PDC and prlogging.xml to point to the hostname instead and this fixes my problem.