Yes, that fixed it. The form expands to the size of its container/parent, in this case none of the containers defined a size for child elements. So the container was small and the form didn’t expand.

Do note however, that in your own Live Preview page that the container of the modal display form is also not large enough to display the form. Perhaps you could fix that just so that we can verify that with the proper container the forms will render correctly.

Thanks.