I have many products that are made to order and BOM can go negative.
What I noticed is that if I want to change, let's say, -20 to -19 I can't simply press the up and down arrows.
As soon as I select the number to change the quantity it goes to positive.
i.e. if I select -20 it will show "20", then I have to manually put "-19".
I don't know if this is intended or not, but it's quite frustrating.
Hope it gets fixed.