On the view screen, with time tracking on and sub tasks, you see the "Time Tracking" section with "Issue & Sub-Tasks" selected. To switch to the other view you have a link "Issue". When you first see this it's not all that clear what this is view is going to show. (It shows the time tracking info for this issue only)

Some thoughts:

• Consider "Issue Only" rather than "Issue"
• Have a longer descriptive title attribute (for tooltip) for both links (when they are links)