icloud mail topic not matching contents

I have one alias in iCloud mail. When I download my mail often, if there are several pieces of email, the brief heading and starting text in the center column of Mail will be switched around between pieces of email. This means that the heading and beginning text shown in the center column will be for one piece of email but if I click on it to show the contents in the right most column, I will get the contents of a different email message.

I thought this problem might be with the Mail app, however, if I log onto iCloud with a web browser, and look at email for this alias, I see the same thing.

I don't think this is related to a particular Mac, as I recently upgraded and still see the same thing.

Anyone have any idea why this might be happening?