Some actions are only applicable for Content Items, like actions related to Permission Sets, AI Tagging, Layers. You cannot use Permission Sets, AI Tagging, or Layers for List Items. Nonetheless, actions are not filtered by the Trigger Point Document Type. That means that you can create a Business Rule for List Items with an Action that should assign a Layer. Picturepark will ignore these actions, skip them and look for valid (e.g. available for List Items) actions.