Grouped Field Headers Only Showing for Site Admin

I have a view that groups results by the value of a CCK field on a particular content type. However, using the field value as the header is only working for the site admin account. For all other accounts and anonymous viewers, the view displays, but without the headers for the grouped sections.

Here's what I have tried so far...

Disabled all views plugins and other modules that may interact with Views (Quicktabs, Views Accordion, etc.)
Changed to table style.
Disabled and cleared caches.
Rebuilt the view from scratch.
Updated Views from 2.08 to 2.11 (issue present in both).
Cleared browser caches in all browsers (Chrome, Safari, and FF3).
Updated core files to 6.19.
Checked all permission settings for authenticated and anon users (Didn't find any that pertained to grouping).
Rebuilt content permissions.
Gave all users "access all views" permission.

None of these things had an affect on the issue. If there is ANYTHING else that I should try, please let me know. It is very important that this view group by this field and it is the biggest hurdle before the site goes live.