They may not be able to share the file. Maybe it contains sensitive data which they can’t release, and they can’t reproduce the problem with other non-sensitive data such that the underlying problem can be determined. Unfortunately, this is very possible if dealing with things like medical records, financial information, government data, etc. I definitely understand that it is frustrating from a development standpoint (as I have experience it directly from a support standpoint), but sometimes people simply can not share what would be most useful for a developer. Perhaps a better approach would be to offer to create a debug version of the app which targets the particular area the problem concerns and ask the person to run that version on their data and report back what they find, giving them the option to scrub out anything which might be not-for-everyone’s-eyes. That would at least allow some level of troubleshooting data to be shared.