Just to update everyone on my investigations:
- 'SELECT position, id_field, field_name FROM smf_custom_fields ORDER BY position;' will show the names of the custom profile fields and the current order in which they will appear on the registration page.
- When I did this, I found three fields with Position =16; that seems wrong. Should Position have a 'Unique' attribute? If so, this would be a change in SMF itself.
- 'update smf_custom_fields set position =17 where id_field = 31;' will move the field with ID=31 to Position 17. Change the Position of the fields to fit your needs.
However, after eliminating the duplicates, 'Order Custom Profile Fields' still does not work. I can drag and drop fields, but as soon as I refresh the page they are back to their original positions.
@Jessica., how many custom fields do you have? It seems silly to think that something might have a limit of 16 custom fields, but 16 _is_ a magic number, and that is where my duplicates were.