So, I had a thought about this. Since the removal of the material for marks exchange wasn't mentioned in any notes prior to the DLC and since they did institute a new exchange of marks for materials, what if they didn't intend for the material for marks to be removed? I haven't read anywhere about anyone at Bungie/Activision even acknowledging that the original exchange system was removed. Kind of like how we lose ammo when we die or how heavy ammo on the ground disappears when a rocket is fired in the area. They only just recently acknowledged the heavy ammo issue. What if in the process of instituting the new exchange system some code was overwritten or screwed up? Just a thought.