Login_hint not passed to ADFS SSO configured via SAML

@lihua.zhang 's article Pass login_hint to SAML provider - Auth0 Community mentions that this works only with Identifier First set as the Authentication Profile.

Identifier First does not work with custom login page.
The passing of login_hint or any other parameter to SSO configured via SAML should be made easier than putting such restrictions of specific use only (especially for some common parameters like login_hint)

My login url configured in SAML connection if appended with ?login_hint=abc@xyz.com (when used externally) works just as expected. This makes it clear that auth0 is not forwarding this parameter to the adfs sso during login.

Has anyone found a way to workaround this? @Auth0, any plans to make this work?