Mail left unread on Gmail server

I read my mails on EM client and after they are read they are marked as read. Now if I access gmail from my office laptop, all emails read on EM client are still marked as unread.

It makes my email management duplicate the effort. Is there any solution to this?

Note: IMAP is enabled

Honestly, it does sound like one of them is using POP3.

When you have the message marked as read in eM Client, open the web interface for GMail and see what the status of that message is.

I just checked. I have POP3 disabled. Once I mark it as read in EM it is still unread in gmail web app or iphone app.

If you right-click on the All Mail folder in eM Client, and choose Properties > Repair, does this change the status in the web interface for subsequent messages you read?

Does not work, I have sync of all mails dating back to 2009. Is it something which can be a problem?

I would suggest that you remove the GMail account from eM Client, and then add it again. It will then be in sync with the server.

I did it multiple times, should I do it as an IMAP rather than gmail setup?

No, the setup is IMAP already, isn’t it? If you go to Menu > Tools > Accounts, the GMail account has an IMAP and SMTP tab, correct?