We have had Certificate Based Authentication (CBA) working on iOS for email, etc. If the user opens portal.office365.com and gets redirected to our ADFS they eventually get "No valid client certificate found in the request." We have forms authentication disabled for Extranet so we can only use certificates.
For some reason Chrome and Edge aren't submitting the certificate. Everything works fine when using Safari.
This issue started about two weeks ago (we think). We are thinking either an iOS update broke it or a windows update. Anyone else seeing this?