House requires updating
You can check if a structure meets the requirements by using the Housing Menu's top button, labeled with a question mark ("? NPCs generally retreat to their Houses at night and remain in them until dawn.They will also retreat to their houses during a Solar Eclipse or Rain.The Housing menu allows you to check whether the houses you have built are suitable for use or not, as well as to manually appoint a house for a specific NPC.To access this menu, click on the house icon in your inventory.
When you first meet the spawn conditions for an NPC, a random house will be assigned to them from your available empty suitable houses.
Certain naturally-generated structures can serve as Houses and may inadvertently attract NPCs if players have placed light sources within them.