Any idea why iteration dialog is empty for planned for in the RTC 6.0.3 Web?

We are using RTC 6.0.3 and have noticed that for at least one project area, the iteration selection dialog for the planned for field in the Web is coming up empty.

If we open the work item in the web and click on the Planned For field we see a small list of the iterations for this project/team.  We then click the '...' button to bring up the dialog to select the iteration from the full list.  The resulting dialog comes up empty.  The project has one timeline with a fairly simple iteration hierarchy.  This timeline is set as the Project Timeline.  The work item categories are currently mapped to the project level so the work item itself is marked as a Project level work item.

We have other project areas that show the correct values in the dialog.  Does anyone have any idea what might be going on?  The process template is a slightly modified version of the SAFE 4.0 Project template.

Thank you,

Jamie.