You install Debian in the BIOS compatibility mode (Legacy BIOS), but Windows already installed in the new UEFI mode. It is cause
grub doesn't see Windows bootloader and you can't choose Debian in the Boot menu. It can be booted, but only directly from hard drive (SATA: ST2000...) To fix this problem is needed reinstall Debian in the UEFI mode too.
From Debian wiki
On the PC architectures (amd64 and i386), UEFI-based firmware is a
relatively new replacement for the ancient BIOS (Basic Input/Output
System) that has existed ever since the PC was first developed in the
1980s. The old BIOS systems have strict limitations due to their
ancient design, running in 16-bit mode with access to only 1MB of
memory, and limited access to other resources like disks. UEFI
firmware is normally fully native and so should be able to access all
the system memory and all the devices.
For the sake of backwards compatibility, most current PCs using UEFI
also include a Compatibility Support Module (CSM), extra support code
that will continue to boot in the old BIOS style. Over time, this
support will most likely be phased out. Some systems were already
being sold UEFI-only (i.e. with no CSM) in 2014.
For installing Debian in the UEFI mode, it is needed:
- Insert your media for installing (USB, DVD)
- Enter to the boot menu while PC starting (holding F8 in my case - Asus motherboard)
- In my computer, I have two item for this media in the boot menu - one for Legacy BIOS booting and other for UEFI booting. Select the UEFI item.
Second variant (I found example's photos in the internet)
Disable Compatibility Support Module (CSM) in the UEFI settings:
Or change Boot mode to the UEFI, like this:
Then the Debian installer splash screen will say it's the UEFI installer, and will look like this: