I've tried to add the Scancode Map key to HKEY_CURRENT_USER with value
00 00 00 00 00 00 00 00 02 00 00 00 1D 00 3A 00 00 00 00 00
I've also tried adding an extra dword of 00s to the end as suggested for windows 8.1 in this answer.
I've restarted after each change.
Sadly, I cannot use the HKEY_LOCAL_MACHINE version of the key as my wife needs caps lock.
Is there a solution to this?