See my post #100. Have you installed Windows 8.1 in UEFI mode (GPT disk) or in BIOS-legacy mode (MBR or Hybrid MBR disk)? In doubt, run msinfo32.exe and in System Summary, see the BIOS Mode value (it can be UEFI or Legacy)
The MacBook Air Mid 2012 11" (nor sure about your 13" model) doesn't work in UEFI mode but it works in BIOS-legacy mode with the several versions of Intel drivers for HD Graphics 4000.
