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?