After updating to FCU (Fall Creators Update), Windows won't boot using Legacy bios mode

Hi, I am using Alienware 15 R2 on the latest bios 1.3.12. Recently, FCU was pushed to my computer and ever since then my computer won't boot using Legacy ROM. I have installed Windows 10 using Legacy mode and had no issue using it until now. Windows does boot using UEFI mode, but I have issue using Alienware Graphic Amplifier on UEFI mode, so that is no go. 

Error message says something in the line of "Boot partition not found" even though my SSD is detected in BIOS. Has anyone have this issue? So far, I've reinstalled windows and stopped the update, but I can only stop for so long.