This could happen when the syncing did not complete correctly.
Determine the computer, either a
Roaming Workstation or Local Workstation that has the correct version of
the sale or order. Meaning the one that has the correct line items.
Then, open that sale or order and perform a purchase order reset.
Upon resetting and saving the sale or order new purchase orders will be created. If the sale/order had already been synced then the new purchase orders will be synced automatically. If the sale/order had not been synced before then sync as normal. Once they appear on the local system you can send them to vendors.