MBP 2016 15inch - Aorus Gaming Box GTX1070 cannot work after upgrade to High Sierra 10.13.2
Have you tried reinstalling Windows? Perhaps the Update of macOS messed with the bypassing of the dGPU.
I would just try to delete the Bootcamp-partition and then do a clean install of Windows and everything needed for the eGPU (apple_set_os.efi, etc.).