As I have explained in my earlier posts on ITS. ITS in OM has 2 phase.
First Phase related to Order Management and it updates the OM related data.
Second Phase related to Inventory and it updates(increment/decrement) inventory related data.
If first Phase failed , system will not execute the second Phase, even if you try to run the 2nd phase directly by executing the concurrent program "Inventory Interface".
Point that I want to make in this post is , On oe_order_lines_all table we have a field reserved_quantity , and will show the quantity that has reserved against the order line, this field will shows the reserved_quantity till "Inventory Interface" part of the ITS has not exedcuted sucessfully.One that is executed sucessfully this field updated to NULL.
Some time I have notice that even the order line is close and workflow is ended , but the reserved_quantity field has still value , which is very very confusing , but latter in I found that in all such cases Inventory Interface part of ITS has not executed sucessfully.
So when ever you encounted sych cases make sure Inventory Interface part of ITS has executed sucessfully.