The effect Delay has got a switch button which inverts the polarity on odd channels. When I assign a MIDI CC to it, it will only activate when the CC sends a value of 127; every other value will deactivate it. But the behaviour of the other switches in Pianoteq is to activate on values 64-127 and deactivate on 0-63.

You won't notice this when using a button on a MIDI controller, because it sends 0 for Off and 127 for On. When using a continous element however, this could be quite irritating.