Got a NIB PS/2 JIS layout keyboard today, but as is only about half the keys send any scancodes / characters on my German Windows 10 machine. Wanted to mess around with it, remapping the thumb keys to modifiers etc.

For example, 'a' works fine, but 's-g' don't do anything, 'hjk' work etc.
As the keyboard doesn't have any dip switches or anything like that, I'm just wondering if maybe there is a software setting in Windows that I would need to change for the board to work in some kind of standard ISO / ANSI mode.
I sure hope it's not broken (it really came NIB), maybe someone here can shed some light?
Thanks!