CityPurchaseBuilding bugged?

[Thalassicus]

When the active player purchases a building ProductionPanel.lua runs this code:

elseif (eOrder == OrderTypes.ORDER_CONSTRUCT) then
  Game.CityPurchaseBuilding(city, iData);
  bSomethingPurchased = true;

I added a call to one of my own events:

elseif (eOrder == OrderTypes.ORDER_CONSTRUCT) then
  Game.CityPurchaseBuilding(city, iData);
  bSomethingPurchased = true;
  LuaEvents.BuildingConstructed(player, city, iData);

Sometimes Game.CityPurchaseBuilding executes (plays sound, deducts gold), but does not actually place the building in this city. This is perplexing! The function is in the game core only Firaxis has access to, so I can't directly figure out what the problem is. Does anyone have a clue what might be going on?

Further info:

Spoiler :

LuaEvents.BuildingConstructed = LuaEvents.BuildingConstructed or function(player, city, buildingID) end

function OnBuildingConstructed(player, city, buildingID)
	log:Info("BuildingConstructed %15s %15s %30s", player:GetName(), city:GetName(), GameInfo.Buildings[buildingID].Type)
	MapModData.buildingsAlive[City_GetID(city)][buildingID] = true
	SavePlot(city:Plot(), "buildingsAlive_"..buildingID, true)
end

LuaEvents.BuildingConstructed.Add(OnBuildingConstructed)

function SavePlot(plot, key, value)
	return saveDB.SetValue(string.format("%s_plot%s_%s", MOD_ID, Map_GetPlotID(plot), key), value)
end