BootCamp Win10 clone to external USB HDD

Hi, I have problem migrating from BootCamp to my external HDD.

What I did:

  1. Created image from BootCamp partition.
  2. Restored to external HDD.
  3. Selected on startup external HDD and restarted.

I get black screen with message: Error loading operating system.

What I tried:

I tried to make EFI bootable and legacy boot, none of them works …

Macbook Pro 2012-mid (MacBookPro9,2)
Boot ROM Version: MBP91.00DA.B00
SMC Version (system): 2.2f44

External drive is USB Seagate 750gb.

What I am doing wrong?

It definitely should be EFI bootable to get it to work externally. I have a 2012 MacBook Pro that I can try this one with a Samsung T5 USB-C SSD. I’ll give it a try and see if it works.