Checkboxes not checkable

Support Forms & Blueprints
1

Hi all,

I’ve a checkboxes field in a form made like this (only the extract):

-
  type: checkboxes
  name: dove
  label: Come sei venuto a sapere del corso?
  default:
      option1: false
      option2: false
      option3: false
      option4: false
      option5: false
      option6: false
  options:
      option1: Amici o colleghi
      option2: Internet
      option3: Social (faceboox, twitter,..)
      option4: Mailing list o forum
      option5: Volantini o pubblicità
      option6: Altro
  validate:
      required: true

but both on localhost and in production the checkboxes are not checkable (a live demo here https://www.faunalia.eu/it/evaluation_form.html).

The form plugin is updated and the grav version is 1.6.22.

Somebody has some hints?