Leyrann
Deity
In the classical era, I conquered Teotihuacán from the Aztecs, and kept it after the war was over. Now, some time later, Germany declared war on the Aztecs, and conquered their capital (and only other city). As you can also see from the screenshot, the Aztecs are no longer in the game. After that, Germany declared war on me, and conquered Teotihuacán. A few turns later, I managed to conquer the city back, got to choose between liberate to Aztec, keep and raze, and chose to keep the city. I then offered peace to Germany, where they would cede Teotihuacán, which they accepted. However, Teotihuacán remains "occupied", meaning no growth and halved production. I waited one turn to make sure it wouldn't disappear, but, well, it's still occupied. I can only assume that the game thinks, for some reason, that I'm still at war with the Aztec (note: I wasn't at war with them when they were defeated).