Latency in Item Substitution in the Promising of Sales Order lines

We establish PIM Item Substitution Relationships at the Item/Inventory Organization level for many of our items. The expectation is that once the available on hand has been exhausted for an item that the subsequent Sales Orders for the out of stock item would transition based on the item's relationship substitution configuration.

Regarding promising, it should be noted that we have ATP Rules set and assigned to items as finite based specifically on the items On hand quantity.

Our observations have been that the orders placed near the time (within an hour) of an item's available on hand being exhausted, continue to be promised on the originally ordered SKU only with the promised Scheduled Ship Date pushed out based on the above 'User-Defined Fence'. Meaning 700 days into the future based on the above configuration. It should be noted that we have collections running on an hourly basis.