I had the same problem with this guy over here: https://forum.strapi.io/t/v4-how-to-fetch-data-from-a-collection-type/11695/3 and as the last answer states I can see my collection-types over here: http://localhost:1337/api/collection-type-name?publicationState=preview so my entities is not published yet. So the question is, how to publish them?