I have built an iron farm on a server with four villages but only one of them is spawning golems. For symmetry I use 128 doors in each village and they are all fully populated due to brown coats harvesting potatoes. Now, I know the villages are not merged because the golems are spawning on the platform I set up in the middle of the one village and, if merged, the centre where the golems spawn should have moved. The village spawning the golems is the one I started with and took villagers from to populate the other villages. So, what could be the cause of three valid villages not spawning golems?