reCAPTCHA visual verification test launched without reason

Hello,

I have a Ninja Forms form in the footer of my site.

I had to remove the reCAPTCHA field from the form because the visual verification test was often launched without reason, without filling any field of the form, without clicking the Send button.

This never happened when the form was made with Contact Form 7 plugin, but I decided to use Ninja Forms instead because it is integrated for the forms of the GeoDirectory plugin that is the main plugin of my site.

Which could be the problem?

I look forward to your reply.

Thank you very much for your help.

Best regards.

The page I need help with: [log in to see the link]