I'm also still confused what exactly is the issue and what you are trying to achieve... It's the data that reaches SAP and then an IDoc gets created, so saying "IDoc reached SAP but not created" simply makes no sense. If it's not created then there is no IDoc.
Kindly provide more details and clarify the question if you expect assistance on SCN. Maybe the issue is with your custom FM that you chose not to share with us. How would anyone know?