LAONE

Thanks so much, I’ve managed to get to working looking at your code. Just for anyone who might run into a similar problem.

Change your registration_errors filter from something like this:

add_filter( 'registration_errors', array( $this, 'la_registration_errors'), 9, 3);

to:

add_filter( 'register_post', array( $this, 'la_registration_errors'), 9, 3);

and use the function like this:

function la_registration_errors( $sanitized_user_login, $user_email, $errors ) {
  ...
  return $errors;
}

The register_post hook now kicks in early enough for new-user-approve to check for $errors

Yay thanks Andy, saved my day!
LAONE

Andy, I’ve spent all day with the exact same problem and have gotten to the point where it’s clear that that register_post fires before registration_errors has even been called ( so that there is always a user created without validation )

Thanks for posting how you fixed it, I just wish I could apply it, but it’s not really clear to me how you did. Have you got anymore hints for me? How did you call the validations in the end?

Thank you!