The SetItemSalesValueWhenZero order rule action can be used to set the value on OrderItem to the product price when it is received as 0.
To set up the SetItemSalesValueWhenZero order rule, please follow the guidance below:
Action: SetItemSalesValueWhenZero.
Param: Enter the value you want to set.
Example: Entering 10 will set the sales value to £10.
Conditions: Any required.