How to modify item mass in a change order

Hi everybody,

in a Pending status of a workflow I set up Part.Title Block.Mass attribute to be required for exit. Although I have the modify privilege for the item and the right property configured, I can't edit the mass values when the item is in a change order (CO). However If the item lifecycle is in Preliminary and the item is not affected by a CO it's possible to edit the mass attribute.

Any idea?

My best

Carlos