To duplicate:

1. Add a new contact form via the modal button in the post editor.
2. Choose the second tab at the top, E-Mail Notifications
3. Change/add a custom notification e-mail address or subject.
4. Press Enter to submit the form.

Expected:
It accepts the data from that tab, returning you to the Form Builder tab.

Actual:
It submits the Form Builder form, adding the shortcode to the post editor. Since the E-Mail Notifications form was never submitted, the e-mail address/subject changes are lost.