In order to fix this issue, you need to assign an accepted preferred locale to each constituent. The steps to do so are listed below.
- Create a Query and add the Field Type: Biographical Information and the Field: Preferred Locale.
- You'll want to add 2 clauses, "Preferred Locale equals en_US" or "Preferred Locale is blank."
- Now, you'll need to create a group from the query results and do a Mail Merge.
- Be sure to include Biographical Information/Preferred Locale in the mail merge as well as any primary key (Email/Constituent ID/Member ID) to identify the constituent.
- Now change the Preferred Locale column to use any of the supported locales for your site, such as en_CA.
- Use this mail merge to do a Custom Constituent Import which will change the preferred locale for all of the records.