Strangely, I’ve seldom used Families list but thought that would easily find the people I missed adding dates where it was recorded in Reunion but not copied over.
Ahha. Could that be part of the issue? Did you copy these family records from Reunion? If so, and there was no “Y” when imported then that will answer the question of how you come to have them missing now.
Regarding the record with the date “AFT 1921”, I can’t reproduce that problem, and can’t see any reason for it to happen. Are you certain that one is displaying “no” instead of the date?