Outlook 2016 - new messages received but cannot see them in the Inbox (from outside organization)

I have a user that has Outlook 2016 client installed on a Windows 10 PC.  Now for some reason, when a new email comes in from outside of the organization it shows as an unread email but we cannot see the message in the inbox.  So the message is being received, but we cannot see it.  We can see messages coming from inside the organization.  We can also see all of the messages when logged into the web version of Outlook.  I have created a new profile and same thing - cannot see new message (other than the number of unread messages increase) in the Inbox.  Any help is appreciated!