The "show notices in active window" only applies when you want the notice to be displayed in the active window. Turning it off does not default to showing the notice in the status window, it defaults to using mIRC's own internal method for notices.
If the notice was being sent to the channel, it will always appear in the channel. If the notice is sent to a user, and they are on the same channel as you, mIRC will show it in the channel window, etc.