I did some debug for a new AreaDamage events and seems like they do not manage insiders correctly.
You may have 3 or 4 OnEnter events without any OnLeave events at all. Or you get OnEnter event when leaving the trigger.
Because of that, damage and everything in event-methods is not calculated correctly.
And on top of that there is a lack of understanding different events.
f.e. you can't really tell the difference between those:
OnEnterBeginEvent OnEnterServerEvent OnEnterClientEvent OnEnterEndEvent