問題

At times you might want to allow users to close their own issues, however granting the Close Issues still doesn't make them able to see the close button.

原因

The reason is that other permissions are also necessary for closing an issue, since it involves setting a resolution and transitioning the issue to a "Closed" status.

ソリューション

Grant the user (or group of users) the Resolve Issues and Transition Issues project permissions.