Queue Advanced Format

Some of our users see a different list query format then others. If you 
open a Queue and click Advanced, you see a textarea labelled "Format"

The content of this textarea is identical with the value of 
$DefaultSearchResultFormat defined in etc/RT_SiteConfig.pm

If I change the value in the web interface and click apply, then revisit 
the advanced setting, I see that the value has not been changed.

Any idea what could be responsible for the change to not go through?

regards
david
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