The bug

Iron golems spawn in villages when there are more than 20 doors and 10 villagers. However, this should also happen when the village is loaded in spawn chunks, with no player in the overworld. For example, if I have a iron golem farm in the spawn chunks, with an item being fired into a nether portal every ten seconds, therefore resetting the timer in time to keep the chunks loaded, it should work. However, it does not, even though entities can move and other things are working, such as chickens laying eggs.