'Shop by' navigation block is missing from some categories
Shop by navigation block is also called the layered navigation block. In order to display the attribute filter in the Layered Navigation menu, you have to enable the category as Anchor category. In order to set category, please open category in admin and set Yes in Anchor drop-down. Anchored categories will display all products associated to all child categories (and child of child, and child of child of child, etc.) on that category’s page, along with the products associated directly to the parent category.
