Installed Windows 10 EFI in Bootcamp mode successfully and upgraded+activated (upgraded from Win8.1 Pro), then did a clean install. Still activated. All good.
But after setting it up in Fusion and booting successfully, it broke activation. Windows refused to re-activate in both environments after that, saying the product key was invalid or blocked.
Thankfully I was able to use WinClone to bring my activated copy back for Bootcamp/EFI mode, but now I can't use Fusion without breaking activation.
In the past I would activate Windows over the internet in Bootcamp and by the telephone method for Fusion, but the "free" upgrade thwarts that strategy.
Any advice, or is this a known issue?