Between Allow User Abort and New Window, drop a Commit script step. That may fix it.
My thought is that when the script is initiated the cursor is inside a field (on the Consignment Forms layout?), and thus the record is locked. At the point in the script after the loop is completed you are then trying to go back to that layout, but still inside the new window. David's suggestion would eliminate that, because the record you are on in the original window would no longer be locked. On the other hand, you might want to keep this record locked while the script executes, in which case I suspect simply removing the highlighted GTL step would probably also work—you don't really need to navigate to this layout within the new window, if that is the layout where you initiated the script.