Problems controlling plugin parameters w/ mouse (click&drag)

I’m not able to properly adjust parameters in Cubase’s plugins by mouse click&drag.
When doing so, it either does nothing at all, or when moving the cursor rapidly, gives adjustments
of random variations. 3rd party plugins work fine. Adjusting parameters by MIDI or mousewheel works fine.

Seriously, nobody else experiencing this? Another note about it is that If I click the value itself (the number below any given parameter), then I can drag the mouse and the parameter changes accordingly.