Plan will not calculate pegging for co-products and by-products

Hello Team:

Is it expected behavior that items which otherwise display the pegging calculations in the workbench show "pegging information has not been calculated for item . . . " when the order type is either work order co-product/by-product or planned order co-product/by-product?

Some portion of the dependent demand orders for this item also have this same problem.  It is not universal, but the quantities of the problem rows when summed may be approximately equal to the total quantity of the co-product/by-product supply.  This leads me to suspect that those un-pegged dependent demand orders are associated with the by-product supply orders.  Is this normal behavior?