SAML retain casing

Hi,

in our environment the IdP changed some usernames from lowercase to uppercase. Appian configured for SAML authentication with "Retain Casing" option, returns error code 401. Do you have any experience that the configuration option at docs.appian.com/.../SAML_for_Single_Sign-On.html
can resolve the issue, and can these changes be made hot or do some services need to be restarted?

Thanks!