There can be several reasons for the names to be overlapped as shown here.
<Please see attached file for image>

- the iteration dates overlap on either the parent and/or child projects.
Removing the scoping to child projects may correct the issue if the parent project has no overlapping iteration start and end dates and a child project does.
<Please see attached file for image>

- If no overlapping iteration dates are found it may be caused by either having too many iterations in the release to fully display them correctly in the browser;
- or the iteration names are very long;
- or the iterations are very short in days and thus the names overlap;
- or the browser font size/resolution is causing the chart to be rendered in too small a window.
Shrinking the font or expanding the size of the browser window can also fix this display problem.
<Please see attached file for image>