Copying an instructed works order when using the copy works order button from the works order screen will result in a new order being created at draft status, but after creation it can dock from the from the budget assigned to the work order line before the new order is instructed. When that order then gets instruted the amount is removed again. Duplicating the incorrect order above would also produce the same error
Resynch the budget(s) (please contact support if require) and ensure patches applied.
Maintenance Manager 4500 Fix 18 Build 2 or Maintenance Manager 4700 Fix 15 Build 3