Thanks Alexey! (Why am I not surprised that it's you coming to my rescue?)
That did the trick, allowing me to start my controller list fresh. What's odd is that the behaviour remains - when I add an AZ controller plugin, it does *not* appear in the control surfaces list under Preferences, but *does* appear under the Utilities menu.
Furthermore, the first one I add - whatever it is, whether your plugin, or Act, or Generic, ends up being greyed out and can't be clicked on, but the second one on the list opens the dialog for the first, and so on, so that the last one on the list opens the dialog for the second last one, but cannot itself be accessed at all. Whether this is a bug in Sonar, or something specific to my setup that's conflicting with your plugin somehow, I don't know...
Nevertheless I've managed, with some fiddling, to get the three AZ plugins I want to use - for the Alphatrack, Kore, and OSC controllers respectively, plus my trusty Contour Shuttle (why, you may ask, would someone need 4 control surfaces plus mouse and keyboard? It's a fair question!) more or less working, which was the goal.
Actually the OSC one is not entirely working, as it apparently can receive data from the computer - it updates time, track, volume, mute/solo etc correctly - but can't actually be used to control those things. I'm a bit stuck on this - it's kind of important to my recording flow at the moment to have a wireless controller so I can control things from the piano in another room from the computer - and would love it if you could spare a moment to help me get it sorted; I was going to post on your forum but the site seemed to be down yesterday... seems to be back up now though so I'll drop you a line over there...
Thanks again!