Please email supportdos@larian.com, with a description of the problem and the report.zip file generated by the
D:OS support tool (for the PC version). The report will contain system and game information, as well as your saved games. To reduce the file size, you can delete all but one save from the zip, since this isn't directly related to the saves themselves.
If you notice anything specific that triggers the disappearance, that would be very helpful.