Unable to view mails via IMAP

Hi,

Am am testing my system here with our IMAP server.
Everything is configured correctly as ZOHO shows a green light on the email account.

It will send out emails, and if I look on my account using Thunderbird, I can see that the mail is in my inbox.

However Zoho shows all my email folders, but no emails within them!!

If I configure zoho for POP3, everything works fine by the way.