What happened about two years ago, my excuse for not remembering any details, is that I had this Excel file stored in a DT database, double-clicked it and opened it in Excel, and modified the content. Then when I tried to save the file, I got an error messages and I couldn’t save it back to the database. Instead I had to save a copy outside the database.
This is as I remember it now, at the time I was quite busy and I never tried to track down what was wrong, instead I just started to save all Office files outside the database.
Sorry for not being able give you more details.