Hi guys!
I've had this issue since moving to Office 2013 on Windows 8. When opening outlook internally it will prompt me for a password. Externally is fine, we have configured to use Outlook Anywhere, basic authentication, through TMG.
This only happens on Windows 8. Outlook 2013 on Windows 7 or XenApp do not prompt for password using the exact same settings.
None of the other threads solutions work.