Currently JIRA attempts to validate the issue's reporter when it is being moved. So if the original reporter doesn't have the create issue permission in the target project, then their reporter will be changed.

While this way maintains the integrity of the destination project (reporters always have the create permission), it's usually not that useful and not particularly intuitive. Generally, people want to keep the reporter data, even if the issue is moved.

This becomes an especially large problem when users are "deactivated" by having all their permissions removed, so that still have issues they reported even though they don't have the permission to. When doing things that trigger a bulk move like Issue Type Scheme migration, the reporter information for these issues are lost.

The reporter field should probably be excluded from the move process altogether.

(NB Not sure if a Bug or Improvment)