I have been using Ubuntu for a few months, and was trying to install Windows 10 as dual-boot for software/games that don't work in Wine.
- Ubuntu 20.04 is installed on a 120GB Kinston SSD.
- 1TB Seagate HDD with 250GB NTFS partition where I want to install Windows 10 Pro.
- HDD has the rest of the space allocated as an NTFS partition with ~650GB of files that I cannot lose or back-up.
I used gdisk in Ubuntu Terminal to convert 250GB partition on HDD to GPT as the entire drive was MBR(as stated above I cannot lose files on other partition). I then booted to the Windows install USB and installed Windows 10 Pro on the 250GB NTFS partition, after which it should automatically reboot into Windows to finish the setup.
In my case it rebooted into Ubuntu, I checked the partition in Ubuntu and confirmed that Windows did get installed. I rebooted and got into my BIOS and noticed that the Windows 10 partition was not in my boot order and not showing up at all, only Ubuntu on my SSD and the Install USB.
I tried reinstalling Windows with the partition this time deleted(250GB as Free Space), and created the partition in in install manager, Windows then made a 16Mb MBR partition in addition to the GTP partition for Windows. The results however were the same. Booting back onto the Install USB I entered Command Prompt from Repair option and used the bootrec /ScanOS command which returned that there are no detected Windows 10 installs.
I have confirmed that I do have EFI Ubuntu installed. Any assistance would be greatly appreciated.