advanced Filter in CMSB editor for list field

This is for CMSB not the front end.

I have province/state table and a country table that are fully populated.

I have fields in my contacts table for the country and prov.

I have set up the province to change when the country changes. The ESCAPED_FILTER_VALUE is the country name.

SELECT name
  FROM `<?php echo $TABLE_PREFIX ?>_sc_provinces`
where country = '<?php echo $ESCAPED_FILTER_VALUE ?>'

When I save the record the province updates to the list for the country selected. However when the country is changed will editing, the province select list does not re-populate. I had the impression that this was to update automatically.

Am I missing something here?