Activity Monitor empty
Rebooted the server last night because a drive had disappeared. That drive happened to be the installation location of the Ops Center. Ops Center services wouldn't restart, so I did a repair installation. The activity monitor only has information after 730am today, which is before the repair installation so I don't think that's the cause.
I assume something in the reboot cleared the monitor, but I'm not sure where that might be configured or what might have caused it.