Here is a programming issue you may have faced in your past.
If a platform you are developing against has multiple firmware updates, and your software has a serious yet hard-to-reproduce issue in one of the older firmware, do you consider that as your bug? Should you work more on that or not?
For instance, Nokia does not issue an official document reporting the changes they put to firmware updates. Their changelogs are considered confidential information. So there is no way to find out if that was their issue that they fixed or not.
While it is obvious that more time should be spent to investigate the issue if the software is distributed to platforms with different firmware versions, how do you generally treat issues that are gone with firmware updates?