The endpoint is hit directly after a logout, rather than being accessed by the XUI. This is due to incorrect parsing of the realm during the authentication module's init and storage inside the user-agents cookie.
Steps to reproduce:
i) Configure openam and saml2 authentication module
ii) log into idp via auth module, and then into sp to link accounts
iii) log out of linked account
iv) click 'return to login page' to witness the failure