Expression Pedal Bug?

I found this strange behaviour when using the matrix to route Expression Pedal CC to DDS1 detune(pw) setting a negative value (white zone) has the same result as a positive value (black zone).
Both will result in the same thing as when you move the detune(pw) slider up. I would expect setting a negative amount to move the value down?

Seems very odd behaviour and something crucial for quite a lot of sounddesign tricks.