Daily Recurring iOS reminders disappear after completing them.

I have many daily reminders, and recently I’ve noticed that some are “gone”. It’s as if the last time I competed the reminder it thought the recurrence period had ended—but I don’t have an end date to the recurrence pattern. Just daily. Forever.

(I also have weekly and other recurrence patterns—I’ve only noticed this on daily recurrences.)

I’m on iOS 14.3 (18C66). I have an iPhone and share my reminders with a family member who is also on an iPhone, same version. We don’t have any other decided and we don’t sync to our computers.

I've seen others reporting similar issues in this forum but haven’t seen any documented fixes. We’ve rebooted the phones, deleted and re-added the app, stopped iCloud sync and then restarted (took forever to re-download all our historical completed tasks, but after a few days we were back to where we started but the deleted reminders were still deleted).

any help would be appreciated.