Cognito Own Domain returning blank page with errors in console.

Hi All,

I've added my domain to Route53, created the certificate for it and added it to the own domain section of Cognito. I've then created the alias record in route53 to point to the cloudfront.net URL that Cognito gave me. But when I go to the CloudFront URL or the auth.mydomain.co.uk I specified in Cognito, I get a blank page with some errors in the console, I've pasted them below.

Refused to apply style from 'https://auth.mydomain.co.uk/null/null/css/bootstrap.min.css' because its MIME type ('text/html') is not a supported stylesheet MIME type, and strict MIME checking is enabled.

(index):1 Refused to apply style from 'https://auth.mydomain.co.uk/null/null/css/cognito-login.css' because its MIME type ('text/html') is not a supported stylesheet MIME type, and strict MIME checking is enabled.

jquery-3.4.1.min.js:1 Failed to load resource: the server responded with a status of 400 ()
amazon-cognito-advanced-security-data.min.js:1 Failed to load resource: the server responded with a status of 400 ()

jquery-3.4.1.min.js:1 Failed to load resource: the server responded with a status of 400 ()
(index):120 Uncaught ReferenceError: $ is not defined at (index):120

/favicon.ico:1 Failed to load resource: the server responded with a status of 400 ()
(index):1 Refused to apply style from 'https://auth.mydomain.co.uk/null/null/css/bootstrap.min.css' because its MIME type ('text/html') is not a supported stylesheet MIME type, and strict MIME checking is enabled.

(index):1 Refused to apply style from 'https://auth.mydomain.co.uk/null/null/css/cognito-login.css' because its MIME type ('text/html') is not a supported stylesheet MIME type, and strict MIME checking is enabled.