Sales Order release problem

We have this really weird problem than happens.

We created a shipper for a sales order release and marked the item as shipped. This created a STK-CUS transaction and relieved the inventory by the order release qty. Then they invoiced the customer.

The next day, somebody went into the sales order release, reopened the release and changed the ship by date to reflect the actual ship date.

The weird thing that happened is when they changed the ship date, it somehow reversed the shipping transaction even though the shipment was marked as shipped and invoiced.

In the transaction history, it created a Negative STK-CUS transaction and added the parts back into stock.

Has anybody come across this before? I'm not sure if the act of changing the dates reversed the shipment but it did happen when they did that.

Any ideas?


[Non-text portions of this message have been removed]