Add attribute to ticket screen - New model issue, please help

Hi,

I´m developing a ticket categorization feature. I’ve created a categories model and every ticket belongs to a category.
I´m facing a problem in the frontend. I´ve created the Category model, a CRUD srcreen, and added the relation to the Ticket model. Then, I added the Category select component to the New Ticket screen using the object_manager_attributes table, but it shows empty.
It´s confusing me because if I navigate to the Categories CRUD in the Admin Panel and after that open a new ticket it works perfectly, but not when I reload the screen or if I navigate directly to the New Ticket screen, in that case I see the select component empty.

Thanks for your help,
Lucas

EDIT:
In the constructor of agent_ticket_create.coffee, I’ve added the following code:
console.log(App.Category.all())
It returns an empty array. But if I navigate to the Categories CRUD in the Admin Panel before, once I navigate to the New Ticket screen it logs all the categories correctly.

Why do I have this issue with the model?