Sorry Jason for misunderstanding, but the link received by email is active only if the user is logged in the web site (clicking on the link sent by email). I have tried to reproduce the issue on my web site under costruction, the error received is 404. If you want reproduce the error try the registration on web site, then close main page, click on the link received by email ,the error 404 is there, normally I should have the login page (because the user is not logged in web site) not the user_profile page. Is there anything wrong in the UE or PS4?
Massimo