Custom knob curve?

Hi, I built a custom Patch module with 4 knob B100K which should be linear.

But when I check knob value in oopsy parameter screen I see a strange behavior:
when knob is at middle value is at 0.2 instead 0.5
when knob is at 3/4 right value is around 0.5

So knob curve seems to be exponential instead of linear.

Can someone confirm? Is it possible to change the default curve?