GroupWise 2012 Client not receiving emails but WebAccess is

I have employee who has not been receiving emails in their Windows Client but the emails are in the Webaccess console. The emails show up under UnOpened Items. Once the email is moved from Unopened item to the mailbox the Windows Client can see the email.

The Windows GroupWise Client can send emails out without issue.

What can be causing this?

Sincerely,
Ken