maresj on "[Plugin: Contact Form 7] Additional setting does not save"

I need to add redirection to another page after submitting the form. So I used this code:

on_sent_ok: "location = 'http://example.com/';"

according to http://contactform7.com/redirecting-to-another-url-after-submissions/

However, when I open the contact form again, the field with additional settings is empty.

Could you please help me with this?

https://wordpress.org/plugins/contact-form-7/