Anybody notice that iCloud email not updating as read (sometimes)?

Hi, anybody else notice that sometimes iCloud email not updating as read on iOS devices?

Sometimes when I have read an email on my Mac using Mail, I'll notice that on my iPhone it saying the email has not been read when in fact I it has been. I'll even close out of iOS Mail and re-open it, hoping that would make it sync correctly. This only happens once in a while and I've noticed it happening in the last 2 months.

What do you think is causing this? Is there anything I can do to correct it? Do a hard reset of my iPhone?