I must admit that this is the first time I’ve ever used the campaign blacksmith bench. So I don’t really know if this is a bug or not. However, I am inclined to believe it is. The campaign blacksmith bench is requiring 2 steel bars for each steel reinforcement to craft. In comparison the Improved blacksmith bench is a 1:1 ratio. Has the campaign bench always been 2:1 or is this indeed a bug?
The Campaign Blacksmith Bench is a T3 bench that sacrifices material cost in favor of faster crafting speed, which means that it has 0% crafting costs reduced. This is not a bug and it’s actually written in the item description.
If you care more about your materials, you might want to use the Garrison Blacksmith Bench which does the opposite, and cuts the material by 50% which is better than a T2 bench that has a 25% material cost.