Can't change slug/ add new posts in Strapi

System Information
  • Strapi Version: 3.4.1
  • Database: Postgres Heroku
  • Node Version: 14.16
  • NPM Version: 6.14


I’ve succesfully deployed my Strapi Application on Heroku and set up a Postgres Database as well as Image hosting with Amazon S3 and all of this works just fine. I used the blog starter for strapi so there was a few collection types called articles uploaded by default. I have one more collection type which is just for posting Links and they work fine. But when I add anymore posts of the type article (they include an image, slug, title and content), or change the slug of the existing one, it can’t be read by my frontend anymore. The data should be fetched correctly in json but I’m not sure whether it’s an issue with my Next.js frontend or my Strapi.