Cameron, First thing is the correct syntax for the XML file is <field name="SITUS_NBR" alias="Number" visible="true">
<format usethousandseparator="false" />
</field>
Notice the case and the missing "s" after thousand. If you are one that is using the FlexViewer source code than you can fix the BUG that is causing this.In the MapManager.mxml line 980.is Currently (BUG):pFieldInfo.format.useThousandsSeparator = fields.format.@usethousandseparator;
needs to be (FIX):pFieldInfo.format.useThousandsSeparator = fields.format.@usethousandseparator == "true";