In the case of that support incident, they had followed the tutorial for adding Digital File pro pages to DataAssist insert and update pages.
The idea is to create a hidden form element on the update page that gets the file name from the database, that hidden form element is used in the Default File binding in Digital File Pro, have you done this? The instruction can be found in the "How to apply Digital File Pro to DataAssist Insert and Update pages " tutorial in the how To section of the DataAssist support page:
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