FOR EVERYONE FACING PROBLEMS ON THEIR RGH:

1. Extract both ISOS with EXISO.
EXISO will give you one folder from each disc 

2. Rename each folder as DVD 1 and DVD 2 accordingly.

3. Delete from both folders the $systemupdate subfolder. 

4. Create a main folder named Alien Isolation and copy both DVD 1 and DVD 2 folders inside it.

5. Pass the whole Alien Isolation folder into your USB. 

Here is the tricky part:

XBOX FSD FIle Manager:

Open the USB, and go to the Alien Isolation folder. Copy it into your HDD://Games folder.

Now, go to Games folder and do the following: 

Open the Alien Isolation folder and then the DVD 1 subfolder. 
Search and find the 5345085E subfolder (inside on the DVD 1). 
Copy this folder into: HDD://Content/0000000000000000

Now, go again to the HDD://Games folder, enter the Alien Isolation folder and delete the DVD 1 folder ONLY.

Go to the FSD blades and load the game.  

To me it worked perfectly.  

Enjoy