Just installed the latest Interim Release of Mixbus 3 (1970). It works much much better for me--much more stable. I did a fresh install. My UAD plugins, IKMultimedia plugins, Slate Vsts all work great now as do all the plugins I have tried. The only problems I have noticed is that while Mixbus 3 scans Izotope Ozone 4 and Ozone 5, these plugins still never show up in Mixbus 3's vst folders. Also, EZKeys still crashes Mixbus3, but that has been the only crash since installing 1970 interim release.
It would be nice to be able to use Ozone with it, but I think that even as it now stands, Mixbus3 is finally usable and stable (at least on my machine [Win 8.1 64bit]).
I know this thread is a little old, but I thought since we have mentioned previous interim releases, that I would just update here and not start a new thread.