When posting WIP in the Jobs module, it is critical to ensure that the Job WIP Posting Date is for the month being closed. If an error is made and the posting date is set to the current month, the General Ledger Entries will not be correct. There is an option to "Reverse" only, however, when WIP is re-run, the amounts will continue to book to the future period. There is something in the code that recognizes that WIP Posting Date and prevents going back to the time period intended to prevent misaligned reversing entries. The idea here would be that Microsoft provide a way to fully reverse and reprocess WIP entries booked in the wrong period.