Many times I've seen this and it drives me nuts and would love to see who has a workaround for it. When logging into the FQDN I get a redirect to /ui/api/internal/login/callback. At this point I get a browser error which is different for each browser but is an error none the less.
Chrome:
{"message":"SAML assertion not yet valid"}
Firefox:
SyntaxError: JSON.parse: end of data after property value in object at line 1 column 42 of the JSON data
