Re: Sunset Valley Loaded in Unpopulated

@Kibocca  Did you load the real Sunset Valley, or Adventureland?  The latter looks the same—same layout, houses, community lots, etc.—but is just a test world with only a couple of inhabitants, not the usual households.

Another possible cause of this is using a particular mod that replaces the shells for a couple of University buildings.  Direct links to mods aren't allowed on this site, but this mod is by AussomeDays and is known to remove townies from new saves when it's present.  The solution is to remove the mod before starting a new save, or to only use it when your sims are about to travel to the University world and remove it when they're back home.