Then everything is fine, good, and right with the world.
You see the NOTICE from ChanServ, as you should.
You do not see the somebody-else's INVITE, because mIRC doesn't normally display them. Which seems to be the behavior you desire, too.
If you want to hide the NOTICE coming from ChanServ, then you will have to haltdef the On Notice event.
I don't understand why my On Invite code doesn't trigger for you, because it does trigger for me. But it seems moot at this point, because you don't want to see anything anyway.