Key follow center note off by one octave

In the filter section one can set the key follow hinge note, which is useful.

So I set it to C3 (in order to compare the synth to Invader 2, where it is C3 as well), but when I keep C3 key pressed and change the key follow knob, the filter cutoff clearly changes, which it shouldn’t. However, when I set the hinge note to C2 instead of C3, and then play C3 and change the key follow control, the cutoff stays the same, the way it should be.
But obviously the whole thing is an octave off :thinking: