I have the same. I have an event for one of my wired clients in security center. But if I go to the normal event log in Network-wide > Event-log can't find that event either. Whatever I select as source in the drop-down (for switches or for security appliances).
It's probably a bug as I would expect them to appear in the normal log as well... seeing as there are filter categories for them (e.g. "security blocked file" would be the relevant one for my event).
I'd open a support ticket.