AI Knob not working with Plug Ins

After some time I wanted to use the AI Knob again for programming automation, e.g. with the UAD Moog Filter.
But to my surprise it didn’t work neither in Nuendo 6.07 nor Cubase 7.5.2! I know it worked before. Mouse wheel for plug in control of the same parameters works fine.
How do I get back a working AI Knob function?

System is a HexCore Mac Pro with OSX 10.9.3.

I can add some observations. Sometimes, with some plug in, the AI knob works (Sugar Bytes Turnado) but with most it doesn’t. Interestingly I tried out moving a knob with the mouse wheel and then quickly changed to the AI knob - this works too! But only lasts for some time - if idle, it stops working. Locking is not possible - but works with Steinberg plug ins as it seems. There is definitely something wrong how the different softwares interact. Steinberg, please fix this. The AI knob thingy is a crucial feature of the CC121 - you can’t just ignore this!

The new Fabfilter Pro-Q 2 works with the AI knob right from the start, other plug ins don’t. I now have Nuendo 6.5 and Cubase 7.5 and it gets really frustrating with this CC121 hardware. Steinberg remains silence about the many problems and it starts to become insulting to the customers.

I guess this is up to the different plugin vendors. This were originally set up to only support Seinbergs’ Vst 2.4 plugins(and higher).
The ADK (framework) has later been released for other vendors to use when making their plugins.