Cached Exchange Mode issue in Outlook 365

I have migrated 4 computers from POP email to Outlook 365.  When setting up each users Outlook 2007 mailbox with the Outlook 365 account, the Cached exchange mode box was checked off.  I then imported all 4 users PST files to restore historical emails, calendar info, etc..  After letting everything migrate overnight, I found all 4 mailboxes with a "Waiting to update this folder" message next to "Connected to Microsoft Exchange" in the bottom bar of Outlook. I sent test emails to all 4 accounts but they took hours to be received.  After googling the problem, someone advised to uncheck Cached Exchange Mode.  This fixed the "waiting to update this folder" message and new emails are coming in immediately.  The problem is after I unchecked Cached Exchange Mode, at least half of the historical emails are missing.  When I go back and recheck Cached Exchange Mode, the emails are there again.  What do I do to show all messages without having Cached Exchange Mode on?
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Vasil Michev (MVP)Commented:
Have you enabled Archive for the Office 365 maibloxes? If so, by default every message older than 2years will be moved to the archive mailbox. Another problem might be the overall profile size, Outlook (especially older versions) will not work as expected one the local OST file goes over 5GB or so.

In any case, best thing to do is to check via the Outlook web app (login to O365 portal -> Mail). If the messages are visible there, you know for sure the issue is with Outlook.
carilouAuthor Commented:
The same number of message show in the Outlook Web App as in Outlook.  Most of the messages that did make the trip are from 2011 and later so archiving doesn't seem like it would be the issue.
carilouAuthor Commented:
I'm sorry I mean 2011 and earlier, not later.
Vasil Michev (MVP)Commented:
So what's the size of the mailbox/local profile? Do you have the latest patches for Outlook? Run the desktop setup wizard from the O365 portal, it will check for any missing ones and install them for you.

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