If you're in the process of adding new Categories to your site you should be mindful of a setting in your Catalog Containers, Exclude Empty Categories. If this setting is turned on, when adding new categories you will not see them on the storefront. As new Categories are added they are created empty and thus excluded from the storefront.
To get your newly added Category viewable on the storefront you'll first need to add a product(s) to the Category and then cycle the the Exclude Empty Category setting in the container. Turn off the setting, click save, turn the setting back on and click save.
If you're in the process of adding multiple categories and products to these categories you may wish to turn the setting of prior to beginning your work so they automatically show up on the storefront, then turn the setting back on when your work is complete.