I don't really know how to open your multiplayer save but from the options I see that "No Espionage" is indeed ticked. This means that certain World Wonders (like the Great Wall) and Spy Specialists from the Courthouse and other buildings give neutral Great People Points. If there isn't any other source of these GPPs in a city, the game knows that it should create a Great Person when the city reaches the threshold but it does not know which one, since Great Spies are not allowed. So the GPPs just overflow (you don't lose any). The first valid GPP source (another World Wonder or a regular Specialist) will be used by the game to create a Great Person of the source's kind. You can actually use this as an exploit. Wait till Metal Casting, build a Forge and hire an Engineer --> this should immediately give you a Great Engineer. Or build a Library for a guaranteed Great Scientist for an Academy...