2amigos: ReCaptcha on RegistrationForm

I’m trying to use the recaptcha widget on the RegistrationForm just like I did on RecoveryForm, by following the 2amigos website’s guide. Everything is working fine except that, on the register form, I can’t validate the captcha because it keeps saying “Captcha cannot be blank” due to the “required” rule shown in the image above.
Now, this doesn’t happen on the Recovery form where I too have the “required” rule just like that. I can take the rule out of the code, but I wanted to keep it just like I can in the recovery form.

What am I missing? Is the RegistrationForm just different from the RecoveryForm and I should just remove the rule?

@tonydspaniard1 any idea?