When taking an item from the ground via the inventory menu and right-click the logs show:
16:23:01:661 SCRIPT : SCR_InvCallBack::OnFailed
16:23:01:661 SCRIPT : SCR_InvCallBack::OnFailed
16:23:01:661 SCRIPT : SCR_InvCallBack::OnFailed
16:23:01:752 SCRIPT : SCR_InvCallBack::OnComplete
I discovered this by accident when debugging a game mode I am working on. The operation completes, and this does not happen on drag and drop transfer, so I am confused why the callback triggers "false negatives". Because the callback only updates some UI stuff and item in hands logic it might not have been discovered yet.
It is not causing any problems but could lead to some undesired behavior if modders or other BI scripters expect one inventory operation to work or fail ONCE.