[SOLVED] Sonar X3 + Control Surface Setup problem (Akai MPK261 & others)

Hi All,
Trying to get the Akai MPK261 working with Sonar X3 (steam edition, if that matters).
I am trying to follow these steps:
 
 
MPK261 seems to have installed okay.  Under Edit- Pref - MIDI - Devices I see the following inputs:
MPK261
MIDIIN (MPK261)
MIDIIN (MPK261)
MIDIIN (MPK261)
and outputs:
MPK261
MIDIOUT2 (MPK261)
MIDIOUT3 (MPK261)
MIDIOUT4 (MPK261)
I have enabled them all.
If I play the MPK then it is reading the keyboard, drum pads, controller knobs etc and sending that input out to modules, softsynths, drum modules etc etc.
 
I then go to Edit - Pref - MIDI - Control Surface and choose to add a "Cakewalk Generic Surface".
But when I choose any of the MIDI ports above as the In Port and the Out Port the selection doesn't stick... Those cells stay blank.
And back in the main cakewalk screen the control surface doesn't show any as being available to use...
 
I've also tried selecting other MIDI In Port and Out Ports for the control surface, e.g. Roland TB3, System 1 and an external MIDI USB device, which are all working fine.  None of them will stay selected as the In Port and Out Port... 
 
Have also tried adding an "ACT Midi controller (-1)" control surface type, but same issue.
 
Have tried removing everything, rebooting, etc etc , but just can't get the MIDI In Port and Out Port to stick...
 
So the issue probably isn't specifically related to the MPK, since from what I've read you should be able to set any active MIDI device as the In Port or Out Port?
 
I actually wondered if Sonar X3 Steam edition doesn't allow control surfaces?  Lots of searching hasn't found info on that though....
 
Any help much appreciated!
Cheers,
Aulias.
 

aulias
I then go to Edit - Pref - MIDI - Control Surface and choose to add a "Cakewalk Generic Surface".
But when I choose any of the MIDI ports above as the In Port and the Out Port the selection doesn't stick... Those cells stay blank.

That sounds like installation problem. Surface plug-ins are registered but can not be loaded. Typical reasons are: 32bit/64bit (plug-ins was installed with some 32bit Sonar version), MS runtime, etc. Try reinstall, if you use custom installation settings check that surfaces are selected.

The word "Steam" probably explains the issue... I have recommended you re-installation since usually when some component is not properly installed, there can be other such components. But not in this case:
https://steamcommunity.com/app/241070/discussions/0/540736587127895581/
 
 
In short, try to install control surfaces separately: https://www.cakewalk.com/Support/Knowledge-Base/2007013438/Control-Surface-Installers