Loving the game. Got the explorer edition and have been making great progress. I am trying to complete the world class museum mission on memento Mile and they only task I have left is to get an exceptional rating from the mayor. I have run the visit twice and got exceptional both times but the mission hasn't completed. Is this a big or something I am missing. Any help would be appreciated. 

Is your museum showing 5 stars on the main map? I'm wondering if that's the same problem I'm having. I have 5 starts in all 5 museums, and 5 stars are showing on the map, but my curator goal isn't registering one of my 5 star museums, and I don't know which one it isn't counting.

Same here I keep getting the exceptional rating from the mayor but it doesn't register as complete. Did anyone figure this out ?

Maybe this helps. I tried to get many exhibits to max knowledge. Then I put the other exhibits that were not maxed in my inventory. After the visit I got my fifth star. :)