MCreator issue tracker has been migrated to GitHub.
Existing tickets have been migrated to GitHub. Please open new tickets on the GitHub tracker instead. If you do not have a GitHub account, all feature requests and bug reports from forums are still considered and checked by the maintainers.
You are importing JSON model with .java extension. For mobs, you need actual Java models that can be made with Techne, Tabula or similar Java model supported modeler.