OTP 2FA Problems with DA 2012 R2 and Windows 8.1 Client - Not prompting or OTP Code

Hi 

Just seeing if anyone has come across the same issue with their WIn 8.1 clients not prompting for 2FA once configured with DirectAccess 2012 R2?

I have created the 2x OTP certificates, enabled OTP via PowerShell and set up the RADIUS server but whatever happens the Win 8.1 client does not get prompted for 2FA - They connect seamlessly?

I have also configured the DAProbeUser on the RADIUS server

Any help appreciated

Thanks