If there is a link to an issue that is not visible (perhaps because it is in another project invisible to the current user), the "Issue Links:" box will still appear, even the "Duplicate" and "This issue is duplicated by:", but no link to the invisible issue. This looks buggy to a user that doesn't know why it's happening.

A similar issue occurs when an issue that is linked to is deleted. The "Issue Links" box still appears on the issue linking to the deleted one, but with no links. (it does however still have the old heading) To reproduce: simply link two tasks, delete one, and view the remaining task.