Copying from a PO associated with a procurement contract doesn't copy aales/use tax settings correct

In Peoplesoft SCM Purchasing version 9.1, when copying from a PO that's associated with a procurment contract, the process is not duplicating the sales/use tax applicability settings on the PO schedule and leaving them blank.  After saving the new PO, the header shows $0 for tax/freight and buyers have to access each line/schedule individually to apply tax settings before dispatching the PO.  The copy process, however, works correctly when copying from a PO that's not associated with a contract.  Same result when attempting a copy transaction in an unmodified demo environment, so we're suspecting this might be a bug.  Any feedback would be much appreciated.