Forms upload files using FileUploadElementBlock with iOS in a site with Windows authentication

Hello

Our site runs with Windows Authentication and we have a FileUploadElementBlock and trying to upload a file using iOS. The request comes to the server but then nothing happends and finally we get a timeout and the request is cancelled. No errors or anything in the logfile. 

We have tried to use NTLM and Kerberos as an authentication protocol but same error, the request is cancelled. No private browsing just normal browser. It works fine with android and other devices so this is only an issue for iOS devices.

Is there anyone else that has had this problem and knows why? Is it a bug in the FileUploadElementBlock or do we have to do some kind of configuration?

Versions

Epi 10.10.3

Forms 4.6.1

Regards,

Morgan