I’m having the same issue. The entire website is password protected and when you enter the correct password it ends on a 400 Bad Request where the URL ends with “<%WF_FORM_VALUE_PAGE%>?e=1”
Thanks again for posting about this issue @Julie_Miranda@james@jonask@andrewrubio@Kalli2000
Our team was able to resolve the 400 Bad Request on password protected pages. Can you please refresh the Designer, Republish your project, and check to see if the issue is resolved on you end?