Im having the same problem though I think I figured it out. In general I create my events from emails and when I do this, Mail will auto populate my Calander event with the necasary information, including the address if available. However creating an event in this manner will not display the map and weather information within the Calendar event.
So I started messing with it and found that the weather and map only show up when you create the event manually in Calendar. When you begin adding an address, Calendar begins auto searching for the address. When you select the address from the suggestions, only then will the map and weather show up in the event. I'm not sure if this is a known bug or what, but it's a little annoying when you have to manually create the event for the map and weather feature to work.