Membership 2 Pro - Signup button just refreshes the page

When the user clicks on 'Sign up' button, the page just gets refreshed. If I'm logged in as an administrator, it works fine.

Earlier, I was getting an issue with payment button because of Yoast SEO plugin. As per resolution provided on https://premium.wpmudev.org/forums/topic/membership-2-pro-user-registration-fails#post-1290176, it was resolved. Now, I'm not sure why this is happening. I even tried deactivating Yoast SEO plugin.

What can be the issue?