Email not shown as being already read

[cronmorgan]

(I previously posted this issue on the device-specific forum with no response; hope this is a more appropriate forum.)

I'm using a Samsung Tab4 10.1 tablet with it Kit Kat (4.4.2). If I read an email on my DESKTOP (say Gmail or Yahoo!), and then go to my tablet, do an explicit email sync, that message is still shown as unread. I must explicitly open the message with the tablet's email app (native email app) before it will display as having been read.

Does anyone else notice this? It it by 'design'?!? Very annoying.
Thanks.