We have been using Orders and Order Products for about a year in a really fundamental way, just to feed into a custom built Invoice object. It's recurring monthly Invoicing, so the values on the Orders can change from month to month. I am now suddenly getting errors when attempting to edit some Order Products that "You can't update Quantity because the order product has been reduced." I understand from Salesforce Documentation that Order Products are not editable after they have been reduced, I just can't find any explanation of what "reduced" means.
We have the 'Reduction Orders" option ticked in Setup, but we've never created any that I know of. I don't actually really understand what they are, as we sell services and don't do returns. I thought maybe just deactivating an order, reducing a quantity, and reactivating the Order might trigger this behavior, but I haven't been able to reproduce it on other orders in that way. I haven't yet found the commonality in the Orders of ours that are displaying this behavior.
What does it mean that we've "reduced" the Order Product? How can I replicate it/avoid accidentally doing it in the future? And is there a way around this limitation now that some of our Orders are not editable, or do we have to scrap them and create new ones?