Jetpack blog subscriptions will not confirm

After upgrading Jetpack to 3.4.3 a new problem appeared with the blog subscription process. Problem still continues with version 3.5.

Subscription widget was working fine, then with 3.4.3, everything seems OK, but the email sent to confirm the subscription does not work. The “confirm” button does nothing. The widget displays the message on the site saying an email was sent, which is true, but you can’t confirm the subscription because the button in the email does not do anything.

Disabling plugins does not work, same problem on all of my sites using both Genesis framework and twentyfourteen theme. No other changes were made other than the updates to Jetpack and WP.

Ideas?

https://wordpress.org/plugins/jetpack/