Some categories are blocked, like daycare and schools. They'll also prevent anything from showing up, pokemon included, from areas that don't have recognized r

Some categories are blocked, like daycare and schools. They'll also prevent anything from showing up, pokemon included, from areas that don't have recognized roads or paths. There is a park near my house that has a paved path through the woods that doesn't show up in the pokemon go app, so nothing appears there because the game doesn't want to encourage you to wander through the woods.