I've had this happen in numerous circumstances, with different Civs and different items, but if you deselect one or more of Your Offers then let the AI fill it back in, every now and then, the terms will be downright silly. I got one civ (Tomyris) to eventually offer me a city for 1 GPT. Pretty sure this isn't supposed to happen. Got her to give up 3 cities this way, as well as all her gold and GPT for one of my strategic resources. I could've pushed it further and got all her great works if I had space for them.
http://steamcommunity.com/sharedfiles/filedetails/?id=788156259
Also, after trading a city in the diplomacy screen, if you meet a civ because of that new city, the wrong character model shows:
http://steamcommunity.com/sharedfiles/filedetails/?id=788157216
v1.0.0.26
http://steamcommunity.com/sharedfiles/filedetails/?id=788156259
Also, after trading a city in the diplomacy screen, if you meet a civ because of that new city, the wrong character model shows:
http://steamcommunity.com/sharedfiles/filedetails/?id=788157216
v1.0.0.26