It would appear that Windows 10 is not quite the plug and play OS that Microsoft would have us believe, more like plug and pray!
Windows 10 is lacking driver support. Our OKI printers worked well under Windows 7 & 8 but 10 seems a bit more fussy.
We will be doing some more investigation but our initial views are that the Windows 10 drivers are far from complete :(
The OKI web site was not too helpful either
However the Windows 8.1 driver works fine but this might not be the case for all drivers.
Our advice is that its best to wait and check that your device does have a native Windows 10 driver available before you upgrade to Windows 10