I have this same problem. I am using LearnDash and Uncanny Owl plugin with WP 2FA plugin. I am using the free version of WP 2FA. I have all the latest versions of Uncanny, WP 2FA, and LearnDash.
With 2FA active and ajax enabled in the Uncanny Frontend Login settings I get the “login nonce” error after entering username and password.
When I have ajax not checked, and I try to login I basically get a page not found error after login and I can tell the login was not successful because my login menu item does not change to logout.
