Required field in conditional section

I have a conditional section in my form. I can add mandatory text and single-level dropdown fields inside this section without issue.

But if I link a radio button field, this happens:

Why is it only radio button custom fields and not others?
Is there a way to work around it?

The meaning of the message is not clear.

Turns out it meant the not-a-form request form (where you edit JSM request types) has the field added and marked as mandatory.

If I remove the field (or better, mark the field as optional) in the form in JSM request type, the Form can be saved.

Since I intend for customers to always use the Form instead of the request type “screen”, I don’t care if the screen doesn’t have all the fields.