update send modal

lib/submitters.rb

@@ -152,7 +152,7 @@ module Submitters
     preferences['send_sms'] = params['send_sms'].in?(TRUE_VALUES) if params.key?('send_sms')
     preferences['require_phone_2fa'] = params['require_phone_2fa'].in?(TRUE_VALUES) if params.key?('require_phone_2fa')
     preferences['require_email_2fa'] = params['require_email_2fa'].in?(TRUE_VALUES) if params.key?('require_email_2fa')
-    preferences['bcc_completed'] = params['bcc_completed'] if params.key?('bcc_completed')
+    preferences['bcc_completed'] = normalize_bcc_completed(params['bcc_completed']) if params.key?('bcc_completed')
     preferences['reply_to'] = params['reply_to'] if params.key?('reply_to')
     preferences['go_to_last'] = params['go_to_last'] if params.key?('go_to_last')
     preferences['completed_redirect_url'] = params['completed_redirect_url'] if params.key?('completed_redirect_url')
@@ -160,6 +160,14 @@ module Submitters
     preferences
   end
 
+  def normalize_bcc_completed(value)
+    if value.is_a?(Array)
+      value.compact_blank.uniq.join(', ')
+    else
+      value
+    end
+  end
+
   def fetch_values_for_delegate(submitter)
     fields = submitter.submission.template_fields || submitter.template.fields
     default_values = submitter.preferences['default_values'] || {}