Use number pad of mac keyboard on Windows 10
Solution 1:
Turns out that the problem was pressing the numlock key. I managed to do that by starting the On-Screen Keyboard from Windows 10, turning on the numeric key pad in the options and then pressing NumLock there.
That triggered my hardware keyboard number pad to work!
Solution 2:
Is case anyone else stumbles across this hitting the "clear" key, just above the 7 will toggle numlock for the apple keyboards on Windows 10.