Hello,
The target menu item setting can be blank, but it will just default to a menu item it can find. The problem above happens, when it finds a target menu item which cannot show the event due to it's restrictions. To avoid this, you set the target menu item to a menu item that can see all events.
It is good practice to have a global url where everything can be viewed from, then when clicking into the event details for any modules etc you would then be navigated to this base url.
Many thanks
Tony