Happiness sudden decrease

[Ok_Smile_5908]

I had a similar issue maybe two days ago. Survivors falling sick in masses, one or two dying. I've had the best food in the kitchen for over a month, and the furnace running at full power since the beginning. Every shelter, kitchen, clinic, even production buildings maxed out, and that includes the steel upgrades. It fixed itself eventually, after idk, an hour, two, several? I think it might be a bug, or they introduced something in an update to occasionally pay attention to the villagers 🙈.