In Windows 8 Professional, Metro Apps and Windows Update do not work with static IP settings behind authenticated proxy server. They work with DHCP on the same proxy settings (we have DHCP for wifi and static IP for LAN, both using the same proxy server).
IE, Chrome and other desktop apps work nicely with both.
Metro apps worked with an auth proxy (DHCP only), when I changed their proxy settings from the "edit group policy" option:
Start → Settings → Edit Group Policy → Computer Configuration → Administrative Templates → Network Isolation → Internet Proxy for Apps
How can I fix this?