Hi @wrightlj , are you saving the return at the end of the day? 

If you saved successfully, and the file has been lost when you wake up, it sounds like something outside of ProSeries is modifying your files.

Another potential issue is that you are working on a copy of the return. In your HomeBase, if you scroll all the way to the right, does the return's file path match what you expect? Do you see rows with the same client name, but with different file paths?

If you continue to see this issue, you may want to back up your files at the end of the day so you won't lose any work.