Read messages on my iPhone sometimes show up as unread messages on my Mac? - 1

I'm talking about email messages. I have my accounts hooked up to iCloud, so if I read an email on my iPhone or Mac, it should count it as read on the other device. It has worked, but sometimes it doesn't. What can/should I do?

This happens to me too between the iPhone and the iPad.

The way I fix it is by REFRESHING the mail on the device that still shows it, then it registers as having been read and it goes away.