Membership 2 Pro and Favorites plugin conflict

There's a Membership 2 Pro plugin on the site and the Favorites plugin: https://wordpress.org/plugins/favorites/ Both are essential to the site, but when they're both active, the membership login page are broken.

To test it, go (with both plugins enabled) to the e....rn.com, and click "Subscribe" in a top menu, then click on "Already have an account?" link under the registration form.

The issue goes away immediately after disabling Favorites plugin.