windows 10 media creation tool not give option for windows 10 pro

I am able to get Windows 10 Professional to install if I disable UEFI & use Legacy instead, but I feel that this is stepping around the issue rather than resolving it. If I try to install using the AIO image from within Windows, the installer does not present me with a list of options for the edition I want to install instead, it assumes that I want to install Home Edition: However it's still installing Windows 10 Home. I then downloaded an All-In-One ISO image of Windows 10 from MSDN (of which I have limited access to), transferred the installer onto a USB stick, & reinstalled (a clean install again). I'm guessing this is due to the Windows 8 Standard Edition serial key preinstalled in the BIOS.

I bought Windows 10 Professional & completed a fresh-install (complete reinstallation) of Windows, only that it installed Windows 10 Home instead of Professional. When the laptop still had its hard drive, I upgraded it to Professional so I could use the resources provided by the domain on my homeserver because of this, I can only use the Professional editions of Windows (Home can't join domains). My laptop (a Lenovo Flex 2 15) came preinstalled with Windows 8 Standard (with the serial key preinstalled into the BIOS), and I've since installed an SSD (a Samsung Evo 840 120GB) & upgraded to Windows 10.

Windows 10 media creation tool not give option for windows 10 pro