That’s why I was asking about the manager and possible conflicts. When you define a form, there’s a lot of metaprogramming that occurs. You’re not actually creating the class, you’re providing information for the metaclass to create the class for you. It’s interrogating the model to find the fields and create definitions. Once those are created, creating the instance will result in a form being created.
The other thing you might try as a test would be to render the form directly (not using crispy). There’s a possibility of some adverse interaction there.
Side note, using standard models and standard forms, it all works as expected. Therefore, I do believe there’s some problem occuring with a third-party library.