The user The Eternal Wayfarer keeps being asked to update their email address because we don't have one on file for them. Indeed, I see that in /admin the user has no registered email address in our database. The odd thing is that they keep entering their email address when prompted, which we are then losing somewhere down the line.
They raised this issue on 1st Feb, but had updated it the same day when I checked and saw their email address in our system. By 4th Feb the issue had returned and we no longer had an email address stored for them.