1) Are you using the Creator code example USB Bootloader project?
2) If not can you try using the same and check if you have any issues?
3) In which version of Win 10 are you facing the issue?
1 - I started with the example and it works fine in Win 7, disconnect the device from one computer attach to the Win 10 and the error shows up. Using Win 7 I can update the FW on the device no problem and the application we wrote that initiates the bootloader on the device works in Win 10; until the device is in "Bootloader mode" and then Win 10 doesn't recognize the device and won't load a driver.
2 - See above
3 - 10.0.14393 Build 14393 64-bit
Can you try upgrading the Windows 10 and check this again? At our end we are able to see this. Can you also try programming the USB_HID code example from PSoC Creator and check if that is working fine?