Steps to reproduce the issue

1. Create a category custom field (text, editor, or media) marked as required and as subform only.
2. If text or editor is your field type of choice, set the field to filter Safe HTML, alphanumeric, or telephone.
3. Go to any content category.
4. The field does not render (as expected).
5. Try to save the category.

Expected result

The category saves as normal, since the field is subform only and not included in a subform assigned to this category.

Actual result

The category errors on save, asking for the required field.

System information (as much as possible)

Additional comments

Additionally, jcfields loads the field in the front end even if there is no content and it is not assigned to a subform.